When you get to stage two of your payroll, Generate Payslips , you are able to access the payslip manager where you can manually override the taxes and add or deduct the STSL(HELP) amount.
We strongly recommended to make a Payslips note stating the additional STSL Loan as requested by the member, so it shows clearly on the payslip.
We have placed this in our product backlog to see if we can set this up ongoing but at this stage this is still pending review