Send an email directly to Judy Mikovits, or the WPI. I'm sure they will either want it themselves, or will know where you can send it. She will be especially interested if you tested positive for XMRV, or if not yet tested, perhaps she will run one for you in any case.
Failing that - try Dr Singh at Utah (who did the autopsy studies on the Macaque monkeys).
I don't know about such labs, but I would propose this to Dr. Singh. She have done studies on XMRV in tissues, and she is currently studying XMRV in blood of patients with ME/CFS. She has the technology to find XMRV in tissues (I don't know if every time XMRV is there, but at least in some of those times).