I recently installed a FMIC on a Mk2 Golf. Couldn't find much info on mounting so here are some pics of how it was done, for anyone converting to a 20v turbo.
Here is drawing of the bracket I used.
Used 50*5mm Plate for the endplates and brackets to hold the intercooler.
30 * 15mm Box for the cross beam. This fits nicely across the bumber brackets. This can easily be mig welded together. I recommend drilling the holes for mounting the intercooler after it has been welded together, as its easier to fit the intercooler this way.
The front panel has to be trimmed, cut the lower section off. and trim the sections inside, and in and around the bonnet lock. This allows the intercooler to fit snuggly.
Here is the brackets mounted with the intercooler attached, the intercooler was purchased from Ebay or alternatively from:
http://www.universal-intercoolers.co.uk/shop.html 
Here is a photo of the bracket and how it bolts to the bumper bracket. Used 2 M8 Bolts and Drill 2 10mm holes.
The radiator needs to be shifted back about 50mm to clear the new intercooler on the passenger side only, so I fabbed up two little bracket out of flat bar, and bolted it to the front cross member and top of the new intercooler. (again easy to bend in the vice, 10mm holes drilled)
Here are some pics of the outlet pipework from the turbo to the intercooler.
I cut the small outlets from the old pipework and welded these back on to the stainless line
Parts Required.
Dairy Stainless 51mm
-2 90 Elbows
-1 45 Elbow
-1 m of pipework.
Silicon Hoses.
- 2 off 51mm Straight Couplings.
- 57mm to 51mm Reducing 90 Deg Elbow.
- 57mm to 63mm 45 Deg Reducer Elbow.
- 57mm to 57mm 90 Deg Elbow
- 57mm to 57mm Joiners.
A shed load of hose clips
Flat Bar 25mm * 4mm
