Invest in a good peak charger most will do Nimh and Nicad. http://www.horizonhobby.com/Products...ProdID=DYN4049
this is what I use for all of my sub-c sport packs. I also use it as a field charger for my reciever packs. Not saying that this is the only one but try to get something with a display that does amps and volts and also has a current adjustment.

No changes have to be made to use an Nimh pack. Unless the connector is wrong you may have to wire a new one on. I don't know if you have a local hobby shop by you but here is one that should be close to you

American Hobby Center
8300 Tonnelle Ave North Bergen,
NJ 07047 (201) 662-0777
Only 3% Sales Tax!!
Store Hours:
Mon-Fri: 9:00am-6:00pm
Wed-Th-Sat: 10:00am-6:00pm