ok ive been doing this for many of my friends, it takes some time but tis worth it. remove the window, clean with a razor blade the part of the window that rides on the seal, (with time it gets a ruber residue.) remove the rear view mirror and then the seal. clean the seal with bleach white. spray the seal with wd-40 and re install all the parts. before you install the window on the regulator, spray with wd-40 again and ride the window manualy up and down just to make sure that the seal is installed correctly. trust me you will be satisfied.
Ps. just make sure that the seal is installed correct, if you need help pm me and i'll help you out.