don't use mdlfx, use .png and text mdls (or the very least mdlc).
Reasons, mdlfx has been known to make buggy images (mdlc doesn't), .png+text mdl is much smaller file size so loads faster (even with the decompression).
There are utlitys to make mdlc and text mdl making easier.
also, mdlfx and stock mdlc only output in 16bit color, as MadP said, text .mdl's + .png's would probably be best. If you have trouble getting it to work, just post the originals and I'll convert them for you.