I just did this today to my v star 650
- it was super easy, nothing to be scared about, and very little to worry about.
I got a 15/32's metal drill bit at Home Depot, was the perfect size for the stock bolt, measured an inch from the stock hole and lined it up so that the new hole would not be too high or too low, but where the shock should sit if it just moved paralaterally forward (if paralatteraly is a word, sounds good)
Jacked up the body of the bike with the rear tire on the ground until the shock was loose and I could pull the stock bolt out.
I had the shock in its stock position as I drilled my new hole, the drill bit scooted right along side the edge of the shock as it went through, it didnt interfere with any wiring.
Lowered the jack a little so the shock moved forward into the new position and put the stock bolt in place, then hammered it in and applied the stock nut.
Blew out loose metal shavings, cleaned up, put the seat and side panels back on and that was it. The hardest part was sweeping metal shavings.
The bike looks awesome, and rides really nice, its my first bike and I feel even more confident on it then I did before.
Someone somewhere said doing this lowered the bike 4", and that didnt make any sense to me when I heard it, if anything it drops it down maybe an inch, and you can't go further than an inch with the new bolt position otherwise the shock will rest up on the frame and won't move forward any further, also you don't have to worry about the shock going anywhere because its contained within the frame and really can't move anywhere. The wiring seems fine, and about the only thing I may do down the road is weld on a couple nuts to the frame to give a little more support to the bolt, but thats probably not really necessary. I highly doubt the frame is going to crack and even if it did the shock isnt going anywhere.
Hope that helps a little with the J Slam or JSlam or Jay Slam mod.