For the sieve stage I don't think so. The algorithm is very difficult, people of mersenneforum.org can't even port the code to windows 64 bits. If I had the skills I would help but I don't have it. Also there's the memory issue, memory requirements grow roughly with the square root of the sieving time. A paper to
read.
For the polynomial stage there's already one. The same client that does the post-processing stage can take advantage of the GPU for the polynomial search. If you look at NFS@Home details/status when you have a number that it is SNFS then no polynomial search is needed, if GNFS then msieve is used to search for the best polynomial.