I once had a similar project. I built a sturdy table from sawhorses- screwed everything together. Anchored two sloped 2 x 4s to the table and at the eave. Drove a screw in each one not quite as high as I could reach from the table, leaving the heads stick up maybe 1/2". From the table I could push one sheet up and let it rest on the screws. This left the top end high enough that I could climb onto the roof and take from there. Before I brought a sheet up, I partially drove two 'resting' screws maybe 4' 2" down from the previously installed sheet. Wrestle the new sheet to let it rest on the screws while I snapped chalk lines, then shoved it into position and placed a couple screws to hold it. This process provides safety and rest breaks in the lifting/handling process.

If your project is like mine, there weren't that many sheets that had to go up whole.