You might find it only has one adjusting screw. I know mine only has one, as I wanted to have it cut out a lower pressure for when using the sandblaster, however the cut-in pressure wasn't adjustable and was a consistent 2.5-3bar lower than the cut-out pressure.
Are you definetly sure your toolchanger needs 100psi?
Any I've looked at are usually around 80psi.

My long term solution is a hydrovane compressor which I still need to get plumbed in, and I'd like to build some kind of control panel so I can set pressures depending on what I'm doing.