Challenging, but doable
It's a puzzler, for sure.
The first thing we did was to tape the receiver blocks into the best position we could manage. Put them in the place you'd want them to end up. Coat the end of the locking pins with lipstick or something, then close the door with the pins retracted. Hold the door as tightly closed as you can manage and then try to "lock" the door, which will extend the pins and mark their position on the blocks. Drill that hole.
Draw the line on the block to mark the centerline of the installation rivets. The blocks do not take marker well, so find the darkest marker you can find and draw as distinct a line as possible, because you've got to find it through the rivet hole.
I had a helper, so I hope the Force will be with you if you're doing this alone.
The next step is to find the hole in the block with the locking pins so you can extend the pins to the "locked" position to grab the block. You don't have to do both at the same time. Once you have a block "pinned" you can try to rotate it either by poking it through the rivet holes, or maybe from beneath with a long handled screwdriver? Get the centerline visible in the rivet holes, and remember to again, PRESS THE DOOR CLOSED before you drill those rivets holes into the block.
At least that's my version.