Hi,
Pushing to Mercurial definitely works as me and others are using it, but most often you don't have the right email or ssh key. Please post the exact message you get after trying to push. If it's a key problem, most likely you'll get Permission denied. If you use linux, you can easily do a test like this on your machine:
ssh -i /path/to/your/ssh/key -o StrictHostKeyChecking=no -l your_email_address
hg.mozilla.orgIf the email and key is correct you'll get the message no interactive shells allowed, if not, permission denied.