I did a lot of cone/seed collection back when was in high school. We managed a couple white spruce seed orchards for a local paper mill and would do control pollination in the spring and cone collection in the summer. In terms of access we used a tow behind lift and placed tarps under the tree to catch the cones. One tool that was invaluable for getting cone off the tree was a hand rake/comb. It was shaped similar to a ping-pong paddle but made out of 3/4" plywood, the handle was about a foot long and the head 5-6" diameter round. Around the edge of the head opposite the handle we would drive 3-4" nails through space close enough together that the cone wouldn't fit thru it but the branches would. we would just rake the cones off. i don't know if your cones are similar and this would work.
This isn't cone collection but for red maple seed we used a shop-vac and sucked the seed off the tree just as it was getting ripe.
If you want me to draw a picture of the rake i can try but my art is as bad as my handwriting, which was similar to ancient hieroglyphs.