The way I read this, the OP wants Mach3 to do something with the reading. I don't see a purpose for that other than for Mach to slow the feedrate or something. I've asked this question several times and the consensus is that feedback to Mach3 for the purpose of reacting with adjustments to a running program is not doable. However, it still seems to me that is would be if the right avenue could be found.
Speaking to this particular thread, 'Pressure' is undefined. methinks. If this means spindle load, that's one cat. If it means the downforce on the head, that's a differnent cat. There are lots of ways to skin them, but skining the wrong one is not particularly useful.