First of all, in order to monitor the system, you will need either the Uniden BC796D or the BCD396T. It's a 9600 Baud Digital Trunk System and the 785D does not support 9600 Baud Systems, only 3600.
If you are programming the 796D, program it as a Type 2/P25 UHF System. For the Custom Frequency Table information, (Base, Spacing and Offset) substitute the 4 digit Offset Channel Number of 8192 (which is listed on the database here and on other sites) with 758. The 796D will not accept a four digit offset channel, and 758 is the acceptable substitute.
If you're programming the BCD396T, I can't help you there except to say that the Custom Frequency Table information is not required for programming it. If you have any other questions, post, and I or someone will try to help you.