Calculated overtime to be spread across two different time types.

I have a requirement where overtime is calculated based on the number of hours worked over a week.

Now once the overtime is calculated the employee has a choice of either getting it accrued in the compensatory leave balance or getting paid for the overtime.

What would be the best way to get this done?

Right now I am calculating the overtime based on the regular hours and once the overtime is calculated, the employee can enter how much of the overtime should go into the accrual balance and how much should they be paid for it. The problem with this is the employee first has to get the calculated overtime and then enter the overtime earned or paid.