Hi Michael,
If you can't find a published atlas, you could make your own template to coregister your group of porcine subjects. The page describing the ICBM atlas gives links to published papers and the software used to make their atlas.
A few other potentially useful links:
http://www.ncbi.nlm.nih.gov/pubmed/20346...
http://www.ncbi.nlm.nih.gov/pmc/articles...
http://www.ncbi.nlm.nih.gov/pubmed/15953...