Hi
2 ways I have just done what you want.
First (and MOST IMPORTANT).. set the Preferences to 'Reset to Saved Value' on Patch change, and Save the Concert everytime you make any changes to the individual Patches.
Create faders/knobs in Layout Mode
Method 1
For each Patch, create an External Instrument Channel set to the correct MIDI Port & Channel.
Map the Faders/Knobs to the required MIDI CC's in the Screen Control Inspector. Set the required control values on the screen controls. Save Concert.
Repeat for every Patch.
Method 2
In Layout Mode, set the screen control parameters to the required MIDI CC's and Channels, and select "Send Value to" the correct Port.
For every Patch, map the screen controls to anything (eg an un-used MIDI CC on a channel strip). Save the Concert for each patch.
Both these methods send the saved value of the Screen Control to the external device here.
HTH
CCT