I found the following instructions from prior years most helpful when usin the Modela milling machine:
FabLab Norway >> http://fablab.waag.org/node/1009
Inna Koyrakh >> http://fab.cba.mit.edu/classes/MIT/863.08/people/Inna_Koyrakh/Week4_PCB_Documentation.html
Nadya Peek >> http://fab.cba.mit.edu/content/processes/PCB/modela.html
Steve Leibman >> http://fab.cba.mit.edu/classes/MIT/863.07/people/steve/usb.html

Modela milling machine and closeup of a 1/64th n-mill milling the dasa circuit board from a 2x3 inch piece of FR1, which is a paper based copper plate.

Using two pliers at the same time to pressure down the plug fixture.