Van Diesel
I don't know if on a 08TDV8 the components are in the same place but I think so.
In the trunk on the right hand side behind the cover for the fuses there is either a black credit card sized box thicker of course with a rectangular black connector with 3 wires (green,brown,red/yell) if I am not mistaken.
If you have the box you have the remote activation. I believe I've come across some pic somewhere on the forum.

If you have the box but not the remote you can buy a webasto Remote on e-bay and readapt it to the system
It is not very complicated question of pulling out a fuse and pressing the remote when putting it back in.
It is all in the manual that comes with the remote

Thanks JAK480, I've got the FBH so will have a look for the little black box. Remotes about £20 on ebay.
Cheers