If a an upgrade bid to CPT opens up in the X, or Excel, or VII or any aircraft in the fleet--you can bid it.
I had several guys in my Indoc class in Oct bid and were awarded CPT bids.
I would hazard a guess that with as popular as the X is and as much as it is used--there will be a CPT bid come up in it before a VII.
The company has the option to waive seatlocks--it is all up to the needs of the company.
Just about every bid award lately-there are some guys that have had their seatlocks waived and were awarded a CPT bid in a different aircraft. But if you want to bid the X for upgrade-seatlock should not be an issue for you anyway.
Hope this helps.