If you do want to use the VW oil cooler(VW recomend a $360 replacement unit every time you work on the motor, but I can find them as low as $85..they DO fail in a number of evil ways)
My way is to eliminate the POS VW oil-coolant heat exchanger Along with 3 hoses and 6 clamps, and one rusty metal tube. I can then use the hose fittings on teh engines for my SVO heater.
I did this by using an air-oil cooler&hoses from a Saab turbo, and thermosttic oil filter/cooler adapter form a Gas turbo 740. saab oil cooler lines worked fine, but they are often old and leaky, so you might want new ones. Get the threaded tube from the gas car too, I didnt, and had to buy an expensive tap to thread my VW/Audi tube deeper after I cut 1/2" off it. A new Oring is also a good investment, $8 at the dealer.

Pictures are here...I don't know why the thumbnails didn't work, but if you click the icons, the pictures work:

http://groups.msn.com/Avatargif/volvoturbodieseloilcoolermod.msnw