K018A DIY Kit 200V 500W Light-Dimmer Module - will it work w/ 120v or is modification required?
Is this it? 



Here's another circuit with the same configuration but different component values. The main difference is the lower resistance of the control pot. Note that the power rating is lower on 120V because voltage is lower but maximum current is the same.



Your circuit should also work on lower voltage, but only part of the pot range will be useful. You could build it stock and note the pot position for minimum brightness, then measure the pot resistance at that position and replace it with the nearest equivalent. 

Be careful - parts of this circuit have 120V on them and could kill you. Use a plastic knob, and put the board in an insulated box so no live metal parts can be touched!