Ah, the Alaskan mill. Makes me appreciate the day I sold mine and bought a Woodmizer.
I simply used 20p nails with mine. Measured up from the log center, drove a pair of nails in each end about 1" or so, put a few down the log if long using a string line, then laid a 2x12 on top the nails for a guide. I cut 30+' long beams doing this, best use I found of a chainsaw mill.