I am in the early stages of construction of my cnc laser cutter and wanted to set up my x and y axis as a mixed control of two servo motors. This meaning I would have my Y axis controlled by simultaneously running both motors forwards or backwards. The X axis would be differential control where running the motors in opposite direction would actuate that axis on it's own. Therefore I need to basically map my outputs of the laser to where the G-code commands a Y axis move, this would directly feed into both motors, then the X axis move would add steps to one motor and subtract from the other in a linear manner.

This is a very simply mix and figured it could be handled by the CNC Controller and not have to be dealt with in a much more complicated manner via G-code generation as it is a very simply add/subtract mix model.

Any thoughts on how to do this? I posted in brain as it made the most sense to me at this time.

Just my opinion...

Because it's a lot more than just modifying a motor's step output - the two motors have to be simultaneously driven in the same or opposite directions etc. "brains" is not going to help you.
The only satisfactory method wit H-Bot control and Mach3 is to modify your CAD/CAM's post processor to write the commands to handle the two motors in place of each conventional X - Y axis move that would normally be written to the Gcode.

Tweakie.