You need to put the red wire from the booser receiver lead plug and put it into the esc receiver lead (remove the red lead from the esc receiver lead and insulate as it is not needed). Now plug the modified ESC receiver lead plug into the programming box, switch on both switches and it works. I have been using this set-up for a year! You will need to plug the booster receiver lead plug with the one black lead in it into the receiver for racing as well as the modified esc lead.

In the pic you can see the Hobbywing Xtreme Stock and RC Dynamics booster. The rx lead from the esc has the red lead removed and tiewraped out of the way. The booster rx plug has the red lead removed and inserted into the esc rx plug. Both the booster and esc plug need to be in the receiver and both units need turning on to be able to drive the model. To use the programming box the modified esc rx plug needs to be used in the programmer like normal but both switches must be turned on.