You need to have a common machine between projects.
Either you can attach the machine you have here to seti and let it crunch a wu; or attach one of the seti machines to this project. The latter, is probably the quickest easiest way. So when that machine that is crunching seti, returns its first WU here, you will see the CPID in MW change to 3f76205c76c98927203c4b4f994f5732.

Hope that made sense. PM me if you have any trouble. It will take about a day for the stats site to catch up btw. You will see it change immediately in you account page here.

Edit to add:
Yea, what Cori said. The first WU that is returned to the project that is out of sync will change it.

Hi! ;-)

You have to make sure to use the same email adress here as on any other BOINC project you're participating in.
After some days the CPID should get back in sync again.