Use an air-powered grinder, or a Dremel to slot them.
As for the measurement...well, you can eyeball it. Or get a small bubble level and sit it on the wheel (after you mount everything) and check it that way. Or just pay $60 and get a real alignment <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt='

'>
Eric