Okay, I'm not sure if you're still in this predicament Duner, but I may have a temporary solution for you.
It is in fact possible to crunch WU on a different rig than the one the WU were originally assigned to. I tested this myself with my laptop and pc.
This assumes you have BOINC and seti set up on two rigs, and you want to transfer WU from rig 1 to rig 2
Suspend BOINC on rig 1, also suspend Network connections
Copy entire BOINC data folder from rig 1, keep a backup just in case.
Make sure BOINC is not running on rig 2. Replace BOINC data on rig 2, with the one from rig 1. (Backup before though, just in case)
Start BOINC on rig 2.
Everything should start crunching, if not, well.. you have your backups.
Once you've finished crunching on rig 2, do the steps above in reverse - transfer from rig 2 to rig 1. Report from rig 1! I'm not sure if reporting from rig 2 will work, but reporting from rig 1 should work.
The reason this may help is if you have access to any other pc thats connected to the net and has BOINC/SETI installed - even if only temporarily.
Theoretically, you could also use rescheduler to change CPU->GPU WU, but I haven't tested this. Might run into problems if you try and report CUDA WU from a pc that doesn't have a CUDA card... again, haven't tested.
Might help, might not
If not, at least it's theoretically possible to crunch stuff on another pc, then report from the original pc. At this time, I haven't figured out a way to transfer individual WU across, and I suspect it's not possible.. but some altering of the client_state.xml might make it work locally, but wouldn't validate once reported (might not even be able to report)