I think it's possible to do something along the line of:
git remote add bitcoin git@github.com:username/bitcoin-git.git
Then you'll only need to do:
git push bitcoin branch_name
git pull bitcoin branch_name
You can also add a commit message by using the -m flag:
git commit -a -m "Check out my awesome bugfix"
This way you won't end up in Vim (and freak out). This is more usefull for shorter commit messages though.