from my experience greasing the roller track itself is a bad idea, as was mentioned previously it tends to cause the rollers to slide and wears them out and in some cases wears flat spots in the roller.
I believe the only places required to effectively lube a mast would be the thrust areas such as the sides of the roller tracks where in some cases there are wear plugs for side thrust. Also there are flat support areas along the sides of each inner-channel, used as guides, and in most cases they have wear strips, lube these areas but steer clear of lubing the roller tracks directly.
The type of grease i use is either endura or some other kind of lubricant that gel's up and doesn't run but isn't solid like EP grease is.

As for how to get up there? Basically its up to you how safe you want to be since there is no precedence set on the "safe way" to do it. I suppose the safest way to do it would be to get a sissorlift or boomlift or some type of platform ladder like rolling stairs or something. A regular ladder would be OK i guess if you had a way to secure it to the mast so it wouldn't slip off.

just my.02 worth :o)