You are right! By chance I did just that (after copying aic7870.add to diskette 0 and adding a line basedev=aic7870.add to config.x) and things seemed to be going along well. It asked for all 3 diskettes, then switched to the cdrom. Unfortunately, after loading in a bunch of files (it looks like the controlling config.sys is the one on the cd) things stopped:
"The file S:\\OS2\\PMSHELL.EXE specified in the PROTSHELL statement on line 214 of the CONFIG.SYS file does not contain a valid program."
The program is present on the cd, so now I am looking for further help. Is this perhaps connected with the os2ldr patch?
Clyde