You will need:
is the best and probably the only way to install it to an r4 clone such as r4 III, R4 gold edition, R4 SDHC etc.)
Latest YSmenu firmware http://home.usay.jp/pc/etc/nds/
to find the file press f3 then paste this into the search bar 2009/03/27 00:00(This will definitely change everytime there is a new YSmenu release)
winrar is a must always. There are some great tutorials here on romulation to install that.
NOTE: I suggest you backup your files in a folder on your desktop just in case, also these instructions work for the m3 and n5 too as the m3 is the same as the r4 and the n5 is a clone of the r4 but it has different firmware files so it is impossible to install it as a firmware, all the other options work though.
1. Extract all the contents from the Ysauto archive to a folder
2. Put the YSmenu firmware you downloaded in the same folder
3. Rename the YSmenu firmware archive to YSMenu0810211800
4. Run the r4.bat file
5. After it does some stuff it will ask you which language the installation process should be in, the options are English, German, and Dutch I believe
6. Then it will ask what flashcart you use, the options are R4/N5/M3
7. After that it will do some more stuff and then it should say press enter when it�s done
8. If you have a skin it will say it found a skin and asks if you want to use it. If you say yes it uses the first skin in your skin folder (if you have an r4, so it would use whatever theme is in your theme1 folder) it will also notify you if it found a GBA frame. Write yes if you want to use this skin.
9. The next step will ask what language you want Ysmenu to be in, the options are English, French, Dutch, Japanese, German or Spanish. Choose the language you prefer.
10. Now here is the important part.
At this point the options are the following
1. Install Ysmenu as a firmware
2. Install Ysmenu as an automatically starting NDS file
3. as a replacement for moonshell(using the middle button on the r4 menu)
4. Like any NDS file
Installing Ysmenu as a firmware only works on the original r4 card, although there are some rumors that it can still work on a clone if you leave in a file that is distinct to that card. For example the r4 III (which is the card I am testing this on) has a file called r4III.dat which the original r4 doesn't have. Supposedly if you were to leave this file in the root of your card along with the other Ysmenu files it would work, but from my tests it hasn't worked, but if I do get it working I will edit this.
Installing Ysmenu as an automatically starting NDS file. This is the best way to install it on a clone if you want to make the complete switch. This method creates an .NDS file that starts automatically when you turn on your DS. Make sure you still have the original firmware for your card.
Installing YS menu as a replacement for moonshell. Instead of pressing the middle button to launch moonshell when you press it it launches YSmenu. This is for people who still want to keep their original firmware and be able to �dual boot� into Ysmenu.
Installing Ysmenu like any NDS file. This will install YSmenu as an NDS file. This is also another method of �dual booting� but instead of replacing the middle button it will show up as an NDS file on your card so you can launch YSmenu from there.
11. After you have chosen your option it will say YSmenu has installed successfully press enter. When you press enter it will exit out of the program. Wait a couple of seconds and if you have winrar (which you�re supposed to have) a zip file will pop up will all the necessary files for the option you picked. Extract all the files to the root of your card.
All the pros and cons of YSmenu can be found here(scroll down) http://gbatemp.net/index.php?showtopic=97615
Personally I �dual boot� YSmenu and my original firmware. I am probably going to make the full switch soon though because it recently found out about YS skin selector. The only reason I kept the old firmware was so I could still have multiple skins but with the skin selector there�s no limit on how many I can have vs. 12 with original firmware and just one with Ysmenu without skin selector.
I made the full switch sorta recently. I now use method 2 on my r4 III and on my original r4 I use YSmenu normally. I am glad I switched everything works better, and I can have as many themes as I want compared to the limit of 12 with the original r4 firmware with YS skin selector
I use YSmenu because it supports GBAtemp's massive cheat database. I can't use it with the original firmware because the cheat file is too big, and there is a patch to fix this but it makes everything Japanese. Also, with YSmenu there is no need for GBAexploader because YSmenu supports GBA ROMs as long as you have a slot 2 card. It will also support SNES, NES, GB, and GBC ROMs as long as you have the emulator in the root(only applies to some emulators I believe, Doesn't work with Lameboy, Snemul, or Nesds)
By Duncan Idaho
Thanks for this information and the link
(this only applies to the dual boot method)
for those who Ysmenu is not working, go and erase the TTmenu and the Ysmenu firmware, seek the firmware that has an Xbox360 background its the one thats actually working, and also decompress the unofficial TTmenu, now you should see several .dat or similar items (r4patch, etc.) those items drag them inside the TTmenu folder, now move the Ysmenu .nds app to the root of the Sd card and do the same for the TTmenu folder, now it should run the game, in case it does not works remove from the TTmenu folder the items you placed inside
im leaving a link with the firmware + the TTmenu alreday fixed for those who are intrested:http://www.mediafire.com/?w1judgwdzlj
This should solve the messed up saves, another thing that can solve it is renaming your TTMenu folder to YSMenuhttp://gbatemp.net/index.php?showtopic=141993
the savlibs and infolibs can be found in your TTMenu or YSMenu folder
make sure you replace those with these
NOTE: this is optional but solves problems for some Saves like Pokemon Platinum
Thanks to: The talented people at GBATEMP for all these files and programs and thanks to Yasu who is the talented programmer behind YSMenu