MIMF

I have a arch top guitar and a Fish man rare earth double humbucker pickup.It is designed to drop into a standard round hole guitar.
I read that Ken Parker dismantles these pickups and re attaches them under the finger rest and at the end of the finger board as a floating pickup.
Is this a difficult thing to do? Would I most likely wreck the pickup trying to cut it apart?

Presumably you can cut off the bass end of the pickup where it overlaps the edge of the sound hole as needed. I'd try sticking it to the end of the fingerboard with double stick tape and have the treble end clip on to the edge of the pick guard. I suspect you will find that it's too close to the strings that way and you'll need to lower it somehow.
The only delicate part of the pickup is the coil of fine wire arranged around the magnet poles or whatever it uses as an armature. Anything outside of that area can be hacked and whacked to your heart's content.

See if Ken would be willing to send you a photo of one of his modified pickups. There are probably several Parker guitar forum pages you could peruse for photos.
http://kenparkerarchtops.com/kenparkerarchtot.html
Chordism also has some photos