Window weatherstripping --- DIY replacement?

[lmk]

I had my driver's window weatherstripping replaced last Aug. Its coming off again at the top and ofcourse I drive more than 12k miles per year, so the replacement part and labor is not under warranty any longer...I do have an extended warranty, but it doesn't cover trim items. It would be $150 to have them replace it again. How hard of a DIY is this? Anyone have instructions..pics are always good too.