Petrol and Conveyance both under Tax Exemption

Dear Experts ,

Need Help regarding exemption configuration under the following circumstance.

My client has a system of paying conveyance allowance only to few employees, and petrol  allowance and conveyance allowance separately to  few of the employees.

Those who get only conveyance for them exemption takes place as configuration is done in v_t7int9

but for those who get split component of Petrol and Conveyance , for them both should be considered under exemption.

suppose an employee gets 250 petrol and 250 conveyance , then both these wage type need to be considered for exemption i.e 250 + 250  = 500 hence 500*12  exemption  should take place .

Please help me experts  how can i  go about this configuration.

Arun