This link is to the Nor' West co in Alaska
[url] http://www.norwestcompany.com/[/url] and they should be able to put you intouch with people who have shot these critters before. Also I would imagine they will be able to tell you about what is available up north and what is not.
You could also check with Powder inc
[url] http://www.powderinc.com/[/url] I am sure they will have info on shipping powder up north. (Is it possible?)
My free advice is (worth what you pay for it)
Use round ball cast of tin/lead mixture, just enough tin to harden the ball for penetration. Wheel weights or lino type mixed 50/50 with pure lead will work.
Have a hooked breach rifle purpose made for alaska. I would take 3 barrels, .62 rifle, 12 or 10 gage rifle and smooth bore to match largest rifle bore.
The .62 rifle would handle all of your normal critter shooting and if loaded stout enough could handle Mr. Bear if the ball was hard enough. The 12 gage rifle would be dedicated for moose and bears. The 12 gage smoth bore would have rifle sights and would be so very versatile up there.
My smokeless rifle would be a top notch .375H&H with quality express sights, a quality quick disconnect scope mount system along with a Leupold 1.5 x 5 Varix lll.
Remember Big animals require BIG bullets and stout nerves.
I hope these ideas help and be safe what ever you do.
Enjoy your adventure up north.