The charge lead polarity simply needs to be reversed. All I do is switch the leads going into the charger. Most chargers have a reverse polarity alarm (check to make sure your's does) so if you forget to switch it back when you charge your next pack you won't do any damage.
Regarding the balancer, if you're talking about this balancer (
http://www.amainhobbies.com/product_...-Poly-Balancer) I can't help you.