i dont do it for a living but have done it alot with my dad(he owns a junkyard) all u have to do is take the trim from around da windshield,poke a whole through the rubber sealant behind the glass,slide a piece of wire thru and tie the ends to something u can hold and put pressure on without it breaking.get a buddy and one of you get in the car and the other on the outside,work the wire back and forth cutting the old sealant and work all the way around the windshield until youve cut all the old sealant. be careful not to cut into the glass. they make wire and these things to tie it around but u can easily makeshift something tho.