The home key can't be used for anything else, because it always drops to the desktop and isn't overridable (as far as I know).
A future version of xmaeme will save the "browsed-to" games in the list, provided they still exist. Is there a specific instance where putting text into a freeform fields is quicker than browsing to a location? (If you put your rom in "roms" on the memory card (roms/nes or roms/gba for other systems), they will be preloaded into the list at startup.)