Thats easy, if you set up your toolbar right, there is a tool called the "Follow Me" tool. It should be right by the "Push/Pull" tool. You have to actually set up a tool bar custom though. You use it like the "Push/Pull" tool, except once you have your face selected you drag the tool along the line you want it to follow. It takes practice to do good.
For my things:
"The Project" is done. I have to get some small things finished, but thats about it. I'll have it done by 9:30 I hope. I'll post the link. You have to download it to understand it good. It's SOOOOOOO nice.