Voluntary HECS Contributions

Hi,

I have an employee that works two jobs which results in a total income that is above the HECS repayment threshhold. Their wage at our business however, deosn't exceed that limit, so the 'Tax Free Threshold + STSL' tax table isn't deducting anything from their pay. 

They've requested that we withhold money from their pay to repay their HECS, is that possible to set up in MYOB?

If so, how?

Thanks.