I must be pischic I seem to remember reading this question a few days ago, non the less a valid question.
I believe the installation manual on Bergy's site gives a good guide
http://www.bergey.com/
http://www.bergey.com/Products/XL1.Tilt.IM.4.pdf
As to how I do it, well I have no experience with ground freezing but guy wires I do.
In the planning stage I measure the fall of the ground at all four anchor points relative to tower base with a lazer level.
I graph them on paper and take measurements off it for my cables. I know I could use a drawing program but such exactness is not required, I simply add two metres to each cable length, I find it hard to weld steel cable. From this data I buy my cable.
I build my tower from base to turbine end, with it connected to the base I make sure the top is equidistant to the side anchors corrected for any elevation difference.
I build one section at a time raise it ensure the tower is level and adjust all cables. If one needs major adjustment ie undoing the cable grips it's easy for a second person to hold the tower. Lower it build the next section, raise it etc. It is very important to continually check side anchor cable while raising to ensure they are not going to tight. This should include the side anchor cables for the gin pole.
Once it's all up I do any final adjustments.
