XWA Concourse & Hangar
Although these are two different areas they are related as the only really good reason to start messing around with them is if you have decided to try for converting XWA to a Imperial based game rather than being content with expanding it.
Looking at the cbms with Stealths viewer ( http://www.darkjedi.com/xwing/ ) it is apparent that there are cbms for a "Regdoor" (which (along with the "Datapad" cbms implies you could have been switching pilots) as well as a "secdoor" (which implies an expansion).
I had a small try at renaming things, didn't make any progress.
As Psychic says in his document on CBM Generation you can create doors to replace TGs own (or indeed a R2 (or whatever) animation to replace MK), though as yet not the main backdrop.
With the hangar you would need a custom OPT to replace the
included Hangar OPT.
If you set a custom mission to fly from a ISD then you will launch (and return into) a Calamari cruiser hangar (or if the number of the mission is set lower than 7 from and to the Azzameen family base).
There also seems to be a problem with the games idea of where the hangar is with a non-standard mothership. The game will pick up on your ships position correctly and give you the option of entering the hangar when you are by the hangar port on whatever ship it is, but when you enter the hangar you will be in the wrong place relative to the hangar OPT.
However if you swap the OPT files so that you have copied (for example) the ISD OPT over the CRS then you do actually enter the Hangar OPT correctly and stop in the right place.
I have not worked much on solving these problems yet.