Anthrax,
Yes you could use the load and uload entities scripts on the fly method for almost any entity. Characters can be a little tricky though I believe they must have a spawn script that allows the main fpi to run otherwsie they will just spawn and idle permanently using the rotatehead fucntion if one applies.
The scripts in the downloaded were really designed for non character entities to aid optimisation by removing other kinds of unecessary entities which would normally add to high poly counts in complex levels.
Being honest its been so long since I made up the scripts that I have forgeotten exactly whats contained in them.
I can write a lot but am poor at remembering things.
Now what was it I was saying?
"I am and forever will be your friend"