1) Typically, UEI remotes that are intended for the cable market can not have the CBL button assigned to a different device via the 992 command. Of course it is possible to reassign the CBL button with a JP1.3 flash cable.
2) No, you can't directly copy an EFC that is assigned to one button to another button. However, let's say that you want to assign a EFC in the CBL device mode, but using the setup code that is (perhaps temporarily) assigned to some other device button. The remote will do that
For example, suppose that you have setup code 1658 (Sony 12/15/20 combo executor) assigned to the Audio button. Let's assume you want to assign EFC 33481 (Preset up on Sony receivers) to the Ch+ button while in CBL mode.
1. Press Setup until 2 blinks
2. Enter 994 (2 blinks)
3. Tap the Audio device button
4. Tap Setup
5. Enter 33481
6. Tap CBL
7. Tap Ch+
The remote should blink twice.
Now if the remote is in CBL mode, tapping Ch+ should send the Sony IR signal for Preset Up.