Can we apply model on the basis percentage of gross salary in Workforce Compensation Plan?

Under Workforce Compensation Plan, we apply increments and adjustments to employees. There is the functionality of models in Workforce Compensation Plans via which we can apply automatic increments to employees, but under Allocation Method of Model, there is no option of Apply increment on the basis of % of Gross Salary. Our client requirement is to apply Increment and Adjustment on the basis of percentages of their Gross Salary. Is there any option in models to apply increments and adjustments on the basis of % of Gross Salary.