How? There would be a LFTR at the polar region, which would beam microwave energy toward L1. The L1 base would then convert that into electricity and back into microwave energy to beam back down to the surface. The surface base would then collect the energy and use it.
The L1 base could also beam energy to geostationary bases which could do the same toward the Earth, but not toward the surface, but towards collectors on VASIMR powered craft. These craft could go to L1 or to other Lagrange points in order to supply them or to crew them.
Meanwhile, back at the lunar base, which is being powered from the L1 base, will be building a Moonstalk infrastructure from the surface up toward L1. Eventually, the two will be linked, so as to enable a crew and cargo easy access from the surface to L1 and indirectly, back to Earth.
Transportation from L1 to the pole regions could be accomplished either by linking up to the L1 station, or by using Space Cannons to launch cargo back and forth.
To start, you would need a base on L1.
From L1, you would travel back and forth to the pole region selected and build a Moonbase there.
You would begin to exploit the materials available there to support the Moonbase and to build a LFTR on the moon. Once the LFTR is built, begin building a microwave transmitter for the Moonbase and a receiver and transmitter for the L1 station.
After this is accomplished you will need one more receiver for the ground where you will begin building a Moonstalk.
You will also need transmitter/receivers for the geostationary units orbiting the Earth. These will be used to supply energy for the VASIMRs, which will be bringing supplies and crew back and forth between the Earth and L1.
Prior to that, you will be using conventional rocketry.
Once the VASIMRs are going, propellant needs will be vastly reduced. VASIMR missions could also bring materials from the Earth, which will serve as an anchor for the Moonstalk. Also, materials can be brought up from the lunar surface as well. Once the Moonstalk is built, the final piece is to connect all the pieces together with the Space Cannon.
Once all this is in place, you can start building your second Moonstalk at L2, on the back side of the moon.
You could also build a nuclear thermal powered rocket which would never land on any planetary surface. It could dock at L2 only, so as to always be away from the Earth, and never pose any radiation hazard towards Earth.
L2 is the gateway to the solar system. Once you have L2 constructed and the nuclear thermal rocket constructed, plus all the other materials in place, you will need only incidental support from the Earth. The moon could supply most of its own needs, plus it could begin to support the outward push to the planets.