To hire Miguel and Karlos in earlier partof game you need copy files fro this archive 
to following path "..ja2\"
Now you have to start new game and you can join rebels to your party... Just press "Recruit".

ATTENTION! It's not patch! It's unofficial bonus to your game :) Because rebels
completely useless in final part of game. When you capture 5 cities they 
like green novice in your party. Enjoy!

P.S. With love from Russia ;)