I don know if there is a demand… I'll write the answer.
RA versions supported by mM are 0.9.7 and 0.9.8.
These versions are designed on premise of mM's retro column. these have a row [Return to mutiMAN] in the menu.
As v0.9.9, this feature has unfortunately been removed.
0.9.8 series has "beta3" built by developer peteUK and the official release version "0.9.8.x".
Certainly… I think there was a bit difference in game could booted each.
Also, and its the same between 0.9.7 and 0.9.8.
if doesnt work with 0.9.8 may work with 0.9.7. In my case, I encountered this with old Game Gear game.
Choice and use the version that your game works well.
Supported cores are fceu, snes9x, genesis plus, vba next, mednafen pce fast, mednafen wsw.
The root'n directory where mM loads roms is hdd0/ROMS/. and create subdirectory under it.
hdd0/ROMS/snes (for SNES)
hdd0/ROMS/fceu (for NES/Famicom)
hdd0/ROMS/gen (for Genesis/SegaCD/SMS/GG)
hdd0/ROMS/vba (for GB/GBC/GBA)
hdd0/ROMS/pce (for TG/PC-Engine/CD)
hdd0/ROMS/wsw (for WonderSwan/Color)
Even if you install 0.9.7 or 0.9.8x and get message "Please install latest version", quit and start mM from XMB again. it should probably work.
edit:
If you update from 0.9.7 or 0.9.8 to the current RA, when you boot RA from XMB the old ver will be started first, so the update will not be reflected.
Therefore, its necessary to devise to use both latest RA and 0.9.7or8.
They can use both by extracting the current RA pkg, repacking after changing the gameID and installing.
The other choice, easier is to install RAce.
RAce has a different ID from official RA, it can coexist with the 0.9.x as it is.
If you are not particular about the official ver, this is recommended.
Also, if you only use for mm retro, no need to keep the old ver RA in XMB.
After installation, copy and save SSNE10000 from hdd0/game directory with the file manager. return to XMB and delete the old RA, after that to enter file manager again, and move the saved SSNE10000 to hdd0/game directory, mM retro can be used.
caution
don't install ver. 0.9.9.x.
mM retro emulators will not work after installing via 0.9.9.