The cuts should heal in a few days
If you can't get your hand/arm all the way up there to get the knob loose maybe you have a friend or one of your neighbor's teenagers that has a smaller hand/arm configuration that would be willing to help you out.
I had my dash out to clean the inside of the guage glass and change all of the light bulbs (as long as was in there) this spring and got many cuts on my hand/arm. Said a few choice words too. My biggest fear was getting my arm stuck up there with no one around and the garage door closed, forgot to have a phone handy when I removed the knob but had my phone within reach when I reinstalled the cluster.
bwostosh is correct, one of the damanding things about this job is to get the knob back in place and screwed on. I have heard that many have not re-installed the knob, are you sure yours is still in place? You should be able to see it with a flashlight, it is white in color and is close to center of the cluster.
Good luck