Remove accrual wage types

Hi Experts,

I wish to remove the accrual for wage types 7010 and 7011 with effect from my current payroll run (Apr 2014).

I understand that I can amend the constant in table V_T511K as shown below by changing the end date to 31.03.2014 (please correct me if I am wrong).

However, I have another requirement which is to retain the accrual for employees residing in a particular cost centre.  I am wondering if this is possible by amending the payroll schema and where should I make the amendments?  I am using a customized payroll schema that has minor modifications from Standard Singapore payroll schema.

Appreciate your help and advice once again.  Thanks!