How Do I Set Up My Light for Constant and Momentary?

So, you've got two options, basically. 

1. Have a tailcap with a constant-on button and a momentary tape switch like the below image.

This is the DS00 Pressure Pad Host and the ST07 Tape Switch.

2. Have a pressure pad that has two buttons, one for momentary and one for constant and a host tail cap like the below image.

This is the SR07 Pressure Pad and the SureFire Scout UE Tailcap for Pressure Pad.

They both end up being around the same price, it comes down to where you want the placement of the buttons.