Where does this hook on to?
 

This hook holds down the fabric on the inside of the top. For the life of me, I can not figure out where it hooks on to.

let me know when you have figured it out
I have the same problem ...

Might it be only used
 

when putting the top in the service position?

no there is one for each side. It hold down the fabric at the corners so that when you open the window the fabric does not fill up like a parachute.

Also according to some, It helps pull the plastic in the center to prevent crimping and avoid the boxster chop when putting down the top.

Fixed it.

For those who are wondering where this goes.....Take off the carpet covering on the door jam. About 1/2 way down, next to the seatbelt retractor there is a slot. The same slot that the cover slides into. Feed the hook down and around, hook it in there and it works great.

I'll need to check mine, as I don't ever recall seeing it; wonder how it got "unhooked" in the first place?