What have you got so far? Would to be great to work on what you've already started...
1. Cable the channel strip to a monitor object and move the Delay parameter to see what midi message is being sent.
2. Next create a fader (button style) and assign it's output parameters values to the parameters of the MIDI values you wish to control. (from 1. above)
3. Set the button's Range to 0_1
4. Create 2 transformers. Cable from the button to transformer 1 and from transformer 1 to 2. From transformer 2 to the channel strip you want to control.
5. Double-click on the 1st transformer and set Data Byte 2's Conditions to = 0
and Operations 'Fix' to whatever value you wish OFF state to be.
6. Double-click on the 2nd transformer and set the DB2 conditions to = 1
and the Operations to 'Fix' to whatever value you wish ON state to be.
7. Hit the button and it should work great.
Hope that helps