The FAA minimum pilot experience requirements to fly as PIC (pilot-in-command) under FARs Part 135 is 500 hours:
Federal Aviation Regulation Sec. 135.243 - Pilot in command qualifications.. 100 hours of that has to be cross-country time, and of that 100 hours, 25 hours has to be night cross country. Most Alaska operators require a minimum of 1000 hours. There are a few who will hire at less than that, but none for PIC positions without at least the legal minimum of 500 hours. Most operators also like to see some Alaska time or equivalent (mountain time) and some time in type. This is probably an insurance requirement. There are occasional co-pilot jobs that come up which require only the commercial, instrument and multi-engine certifications. Penair is one of those companies, but only very occasionally do they have to settle for a new SIC (second-in-command) with less than 500 hours TT. They require a two year employment contract and you barely make a living wage.
Probably the best way to get a job flying in Alaska if you don't have at least a thousand hours or more is to move there and give flight instruction until you acquire the hours necessary. Anchorage would be a good starting point. Take Flight Alaska,
Take Flight Alaska, often hires flight instructors as there is a fairly steady turnover as pilot/flight instructors move on to air taxi jobs. The Aero Club at Elmendorf Airforce base also provides civilian flight instruction, and Artic's Air Academy in Palmer is another.
So in my opinion, the best way to acquire flight time is to give flight instruction. You get paid to do it. You'll learn a whole lot more than you already know and you build flight time.
There is an Alaska bush flying forum that may provide you with some useful information at:
Alaska Bush Flying
Alaska flight operations and Alaska Flying is a good source of information.