You can play all your legal homebrew roms on a flash card and Zerograd is working on a CD burning utility(I think that a beta is available that supports a few games) that allows you to burn several legal roms to a disc that will run them on your Turbo/PCE system.
I've never done this (seriously!), but if you take the 4-in-1 TurboDuo pack-in disk... you can swap out the ROMs (well, i think you have to leave Bomberman on there) and replace them with different ones. I'm clueless on this, but folks at magicengine forums have discussed this (do a search... it was a year or two ago).
Essentially, the TG-16 boots up the ROM from the CD, instead of a HuCard. The only other game I own that does this is Neo Nectaris (you can boot the original Nectaris HuCard ROM from the CD). The 4-in-1 is better (3 ROMS on one disk... but of course the menu screen will still say "Bonk's Adventure", etc....)