Best way I found to get prisoners is to give a routed enemy nowhere to go. I made a battle on CMBO where American force attacks fortified German position on top of a hill. Several times I snuck around back of gun bunkers, after taking many grenades and explosives, my guys would say 'come out with your hands in the air' and the whole German gun crew would surrender. Knocked out four bunkers this way. The rest would try to run through my men to get away, with predictable results.
Anyway, I've never had a problem taking prisoners when I wanted to.