you can do it pretty easily without any speciality tools. to properly level the 3rd axis, you're going to want to be at full draw, but there are some methods to get you in the ballpark from the start.
good video on a diy bow level
setting 3rd axis
https://www.youtube.com/watch?annotation_id=annotation_1674180361&feature=iv&src_vid=cdLvqeOJnCQ&v=Di8DRLjG8fQto get my bow in the ballpark to start, i made a bow level like that one, then clamped my bow onto a level table aiming at a steep down angle. i had to use small pieces of paper to shim the bow to make it perfectly level, but once you have the bow level when aiming down or up, you can make small adjustments to your 3rd axis screw until they're both level.
the other diy way for 3rd axis would be to hang a plum bob from something fairly high up. at full draw line all of your sight pins up with the string when aiming up or down (preferably down if you are doing this near other houses) and see where your sight level is at. let down, adjust, and check again until the sight reads level when all of the pins line up on the string.
good luck
