You still have the second pump pressure feed line somewhere dont you? (The HICAS one)...
If you didnt just block it off at the pump...use that to run the cooler. You dont need high pressure line because there is no pressure, or very little. Just the resistance of the oil running through the cooler and then back into the reservior.
Run some oil hose, EFI hose clamps, use a small trans cooler. Thats what I did, eliminates spillage of the oil out of the reservoir due to expansion during track days etc.
Theyll prob charge u more to make the hose than for the cooler itself, theyre bloody expensive and you dont really need it.