I just modified my standard rivet gun by drilling out the biggest rivet nipple (yup, thats what they are called) by about 1/64" and the plastic rivets fit just fine. The largest size stock rivets also work just fine after this mod as its really on a 1/64".

I have the brushed aluminium ones It took me around 45 mins per side and the most fiddly part is getting the aluminium part to line up perfectly and snap into the fender flares.

David