I need to set up holiday leave where the accrual is based on the number of hours worked.

The hours worked will be imported on a weekly basis and for every 37.5 hours the employee must receive 4 hours of holiday leave. The leave accrual must be prorated, so for example if the employee only works 20 hours in the week the accrual must be 2.133 (20/37.5 * 4).

Any suggestion on how to set up the accrual?