Nope it is not legal to plvl yourself whether it be an alt. toon from same or other account on a different computer. Just pass on the gear from the toon you would have used to plvl to your new toon while leveling up (if you had the foresight and not sold of your gears at the different levels) and you can plvl yourself in that manner
Believe me, it is fun and shouldn't take long when you are sporting dreads in the 30 levels legendary-Goddess in the 40-60 levels, etc. etc.