You can try this :
http://wiird.l0nk.org/forum/index.php/topic,8138.0.html
to remap Wiimote+nunchuk buttons.
unlike the name, it's not universal as each games/developers use their own button mapping. But if they used a common mapping (for example from the same SDK) it could work.
- copy the code into your GameID.txt file located in sd/txtcodes/ (you may need to give a title : put a line before the first code, for example "Remapping buttons B to Z")
- replace the part with the comment in a text editor *
- create the gct (within the loader or with a code manager)
- enable ocarina in your loader
* to edit the code :
this part contains the original button order :
00010002 00040008 # LLLLRRRR DDDDUUUU
00100000 00000080 # ++++WWWW NNNNXXXX
01000200 04000800 # 22221111 BBBBAAAA
10002000 40008000 # ----ZZZZ CCCCHOME
like said in the link above, if you want to replace "HOME" (the last 2 bytes : 8000) by simultaneous A + B button, replace 8000 by 0C00
You can find a button conditional here :
http://geckocodes.org/index.php?arsenal=2
Select the button you want, and look at the "Result (wii)" code.
WWWW = Wiimote shake
NNNN = Nunchuk shake
edit :
swapped B to Z, and Z to B :
00010002 00040008 # LLLLRRRR DDDDUUUU
00100000 00000080 # ++++WWWW NNNNXXXX
01000200
20000800 # 22221111
ZZZZAAAA
1000
0400 40008000 # ----
BBBB CCCCHOME