I have used "mechanica" brand paintable seam sealer in the cheese wiz cans and it worked extremely well for me.
I also used 3M on the last car I did and it wasnt nearly as nice as the mechanica brand stuff I used. It was more difficult to lay a nice bead and wasnt as neat when I was finished. Both accepted paint just fine.
I have also used HV-350 Adhesive from Valco Cincinnati Consumer Products. Its a paintable adhesive sealant that can stretch up to 600% its own length without failing and its got incredible grip. It takes longer to cure than traditional seam sealers though. It can be found at www.*******.com