CSV Member Import

I am building out a new membership site for a client and I've got 12,000 members to import and configure. That is way, way too many to do manually.

In this thread, David suggests writing a script to add them.

I've got a good programmer and a mySQL person to help - can you suggest how we might script this? We can hack up a csv uploader, but since membership is a bit trickier, I thought I'd ask before we spin our wheels on it.

Many thanks!