I just finished an Install on my IQ and I found two tips that may help the next guy.
1) I used some 1/2" EMT pipe (used for conduit, cost $3) as a ruler and cutting guide for the inner edge. This way I could run the grinder/saw accross the tube and get a clean straight edge and since the inner skinz tube is also 1/2" it made for a clean finish and didn't have to measure a thing!
2) I used about a foot of plumbers tape. Yes the stuff used for hanging pipes in your crawl space! Anways, it has 2" spaced holes and can be formed fit to the pipe to make a quick jig. Worked great and made the install of rivets and ice studs idiot proof.