Default [Q] Unlocking HTC Ultimate.

Hi, if I want to downgrade SPL in my HTC Ultimate wich is SPL-4.6. 175006.2(140733) to 2.05 in order to HSPL my device, do I have to use the Gold Card method? I tried to do so with software from DFT but I always get the 294 error msg.
Is it possible to HSPL with SPL 4.6? If so how to then?
Thanks.

Also I don't know if this will be useful but here are informations from BootLoader:
PI39100
SPL-4.6. 175006.2(140733)
eMMC SMS 15028MB, F:PA32
TOUCH A1 (F:81, ID:1, V11, BF8)
Radio- 17.5006.07a.17
HTC Titan