It's relatively easy to do with a long piece of string and a 100ft tape.
I can't describe it easily here due to my shortcomings and bad ascii art,
but the jist is to use trig to get a couple of lengths and then use the
string to repeat the measurements on the ground.
If you have the lengths of all the sides of one of the triangles formed by
the tower and 2 guy points (from the trig) you can lay out the actual guy
points easily. Send my an e-mail address and I'll send you a scanned
drawing of the process.
It's really much easier than I've described it here.