STD (short term disability) calculation at 80% of employee's pay rate per hour

Currently we manually calculate STD payment and enter that in e1 to pay employee.  As you can see pretty manual process and we are in the process of automating this process.  Does anyone out there who can share their STD process where we can review and do the same?

STD payment = hours x pay rate x 80%

Not sure where we can tell e1 to calculate rate at 80%.  Looking at our pay type 1 (REG) setup, STD is going to be very similar to this EXCEPT we need to calc at 80% of employee's pay rate. 

I would appreciate greatly in advance.  Thanks!