Leave Accruals

Hello,

Permanent Part time staff work Afternoons, Midnight & weekends that form part of their Base hours.  How do I set up the leave accruals to calculate using all employment categories not just base hours.    Need this to happen automatically as payroll is 400+ staff.   Currently have them all set at 5.846 per pay period but then some staff get more hours accrued than they should. If I set them as the percentage of Base Hours then some get no hours accrued as they have not worked base hours but have done weekend ,afternoon hours or a combination of all categories.