Hmm. I've built openredalert, and it looks like the problem from FreeRA above still exists. That is, it has trouble reading subfiles from the mixes. Commenting out lines in files.ini is not the answer, as those files are IN main.mix/redalert.mix, and themselves contain the rest of the data files - i.e. fonts etc.
I'm having a poke around using gdb, but I forgot how clunky the command line client is... :S