Bottom bracket too tight to screw in by hand
If one side screws in without problems, and you've verified the thread orientation, then it's not a compatibility problem. ( http://sheldonbrown.com/bbsize.html - scroll down to "bottom bracket threading".)

Trying to gently tighten it with a wrench should be fine. If you encounter abnormal resistance, then you should start thinking about taking it to a shop for chasing.