Stop calculations

I have this script attached two different buttons one to halt the calculations and the other button to perform the calculations:

   // Turn Calculations On

   this.masterCalc = this.calculate = true;

   this.calculateNow();

   // Turn Calculations Off

   // Use Master Calc to control calculations in other areas

   this.masterCalc = this.calculate = false;

What I would like to do is, is to apply these commands to only certain fields, not the entire form and all the fields. Like field1, field2, field3, field4 and leave the rest of the fields alone.

Can someone please tell me how would I add the named fields to the turn on/off calculation script above? Thanks for the help.