Ok I admit it I had my 4Runner rustproofed when I bought it new 3 years ago... anyway, the place I had done did NOT need to drill any holes - there's enough access points (usually covered with rubber plugs) that a good rustproofing outfit should be able to do it without drilling. Remember, drilling the holes breaks the paint seal... and it's usually the first place rust will start.

When I was in college, one of my duties at the dealership I worked at part-time was covering for the rustproofing guy when he went on vacation each summer. Back then (the early-mid 80's) many cars did not have those access points, so yeah I drilled. But from what I've been told, a reputable shop should be able to do it without drilling or otherwise breaking the paint seal. Good luck.