Welcome Molly!

I have been searching for ways to live more off the land here in Alaska
and I read something about being able to use Fireweed plants to spin
with and am searching for the HOW of it... How to go from whole live
plant to usable yarn.

I'm afraid I don't have any personal experience to share with you. I remember reading an article in an old Spin-Off where they talked about spinning a cactus fiber, and how it was similar to other wild fibers like fireweed and cultivated fibers like flax. Basically it was a long process of rotting the outside of the plant without ruining the inside fibers, the washing the fibers, drying them, hackling them to seperate the long from the short fibers, and spinning. In this case it was the broad thick leaves, but I'm not sure where the fiber is in Fireweed.

Basically look at the plant you have available and decide what parts are spinnable. The seed fluff? (cotton) The fibers holding up the stem/leaves/roots? (flax/hemp) The pulp itself? (bamboo/soysilk)

I wish I could remember what issue that was in.

So far you're the first person to ask this question, here's hoping someone else has some experience to share!