You could pay a professional to jet it for you, but where's the fun in that?! Lol. I live for that sense of satisfaction that comes from my job well done. Like my boss' '86 Moto-4 that finally fired and ran today after having been in about 15 major pieces for the last two months.
Anyways, YES, you do have to run the engine at WOT to get an accurate plug chop, but only for a few seconds. Basically, put in a fresh plug. Then, just get out on the straightaway and wind it up through all the gears, shifting normally. When you top out in 6th at WOT, keep the throttle held open, and immediately shut off the engine. Pull in the clutch and coast to a stop. Then, remove the plug and take your reading.
Of course, if you're like me and run out of room to run all too quckly, you can skip a couple gears. The point of this technique is to put the engine under full load at all RPM's for at least 30 seconds. This allows enough deposits to build up on the plug so that you can take an accurate reading. However you achieve these circumstances is up to you.
About the jetting: A pro will be glad to do it for you, for a fee. But, he doesn't own or ride the bike. YOU do. Your quad communicates to you as you ride it. When you feel the powerband coming on at the right time and that sharp Toomey crack in your ears

, you know it's close to being right. Jet rich and lean it out as needed. That way you won't blow an engine, and you'll still have a margain of error.