Need help setting up pension plans in Benefits

Summary: I need to setup basic and supplemental pension plans which allows employees to enter % or actual amounts to be deducted. The amount will need to be calculated as % times of base pay. I need guidance on the best practice

Content (required): We are not implementing

Pension basic and supplemental can have 3 options - Conservative, Moderate and aggressive. Basic has a min/max limit or 1% to 8%. Employees should be able to enter either the % or the actual contribution amount. We have to capture enrollment within benefits as payroll is not implemented.

The rate should be displayed as % of basic salary