yes i have that setup and the dimmers work with the stock timer,so wherever you set the dimmers the lights will stay at that intensity every day until you adjust them again
the instruction pdf suggests drilling the hood and glueing the pots in,i didnt do this but extended the dimmer wires outside the hood as i will be fitting a flora mate controller, if you are going to fit a dawn/dusk controller it would pay you to do the same,one thing i have found with the kit is at 100% (which youll probably not use) they run really hot at least equal to the standard lights,at 90% they are barely warm to the touch,also check out your light lens if its not in great condition it blocks a fair bit of light,i got a new one from stevieT