Non Taxable Allowance

I tried to set up a payroll category to reimburse employee for say accommodation for work purpose, so it wasn't reportable to ATO (so I put "Not Reportable")  and exempt from PAYG Withholding, but how can I enter and amount instead of having an hourly or salary amount?

I also then want to on-bill this expense to a client for payment and charge it with the hours that particular employee worked.

Not sure if I'm making sense, but this is what I need to be able to do and have been on the phone multiple times to MYOB for help and the last time they told me to add it as an employee purchase, but when I read about that I wasn't sure this was right as they aren't actually buying something from the business, and now I can't even remember how I was told to enter that on their timesheet.