Technically, it's possible but the execution is long and tiring. Because LF2 is hardcoded for 500 HP-characters for most circumstances, it wouldn't be enough to simply add an extra-condition upon spawning (so something along the lines of "{procedure that adds objects to the array upon match-start}->{is ID == X?}->{if yes, set object to have Y HP, otherwise continue as normal}").
HP regeneration is coded with 500 max as well. For instance, when you give a char some HP via an itr with a negative injury, his HP will reset to 500 when he starts drinking milk. I honestly don't know how this works with enemy coms in stage mode (whose HP obviously can be defined), some sort of magic that can probably be copied for your purposes.
Lastly, HP bars would need to be drawn according to ID. That's also something weird which I honestly wouldn't want to bother with. There's probably some more things which would act wonky (MP regen speed is based on HP values instead of percentage) but I can't quite pinpoint them right now.
Neora adds a tag to DCing called "ohp" which defines the HP of opointed objects. Your best bet is to have a closer look there -- potentially copying that code for your specific purpose.