V35, fairly easily with the 3.5 using a plugin (platinum pro), hard with the 3L and 2.5. I think the Link would be the better option, and much cheaper than the Motec.
M35, almost impossible with the 2.5det at the moment, no-one has managed to fit a full standalone on the det afaik let alone a manual box.
I would be going with the R33 gtr box personally, as they are 1/4 the price. You can buy an adapter plate from for VQ to RB conversions for around $1k US. Lot's of custom work required, and the V35 manual interior parts required are hard to come by.