Lucas set up

Thought I'd ask the question that I bet other new fellas might be too scared to. When setting up the mill on site what tips and tricks does anyone use to get mill rails level/parallel to each other. I set the mill up the other day on a site and it was on a bit of a slope from left to right as you look at the end frames. Packed up one side and eyed off rails to what i thought was level but was having a hell of a time milling one pine log:(Cuts weren't lining up properly so I'm going to re level...

Source: http://www.woodworkforums.com/f132/lucas-set-up-145562/

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