Has anyone found a good way to install the firewall insulation fasteners? I bought Ricks tool but it didn't help. Any ideas?

I used a homemade version of the tool (a nail with the point ground off) and a friend on the outside pulling with a pair of pliers.
Are you using the plastic fasteners that came with the kit, or the correct rubber ones.
The tool is made for the rubber ones, and "stretches" it into place. The plastic ones don't stretch, so they probably take extra force to install.

Perhaps warming the plastic ones to soften them would help. Are the holes filled with paint or anything, this can reduce the diameter and make it harder to insert the plastic pieces. I just gave up on mine and threw it away. I doubled up on the brown bread sound and heat deadner.

Don't laugh, but using KY jelly on them works well. Because it is water based it dries quickly.

Throw the plastic ones in the trash. I highly recommend using a rubber to get into the hole.