A couple of modifications should be made to the detailed procedure...

if you copy to an external memory card, it's probably going to be FAT or FAT32. chmod probably won't do anything.

I suggest that a) it either be temporarily copied to root's home directory and done from there or b) explicitly passed to the interpreter (probably the best choice) as in:
# sh /media/mmc2/cron/INSTALL

Are there any other problems foreseen with that?