I've been poking around with this myself (http://www.cypress.com/?app=forum&id=2492&rID=58742).
From what I understand, and some one please correct me, is there are two drivers provided by Cypress. One runs on the controller-less graphics peripheral, and the other is the GUIDRV_CompactColor_16 driver. Both are configured to run in a parallel bus setup.
According to Segger documentation, the GUIDRV_CompactColor_16 runs the following display controllers:
Himax HX8301, HX8312A, HX8347
Hitachi HD66766, HD66772, HD66789
Ilitek ILI9161, ILI9220, ILI9320, ILI9325
LG Electronics LGDP4531
Novatek NT39122, NT7573
OriseTech SPFD5408, SPFD5420A
Renesas R63401, R61509, R61516, R61505
Samsung S6D0110A, S6D0117, S6D0129
Sharp LR38825, LCY-A06003
Sitronix ST7712, ST7628, ST7637
I understand that from Segger you can acquire other drivers. Maybe get a copy of GUIDRV_Template from them and you/we can customize? They most likely have already written exactly what you need though.
Oh, since you have a sitronix with similar product number, maybe the compact color driver can be altered with some defines -- I noticed somewhere in the code there were defines that indicated register locations and commands. Of course I forget the exact spot