Custom Delegation of a SharePoint Workflow Task list ?

Hello,

We were required to programmatically Approve,Reject & Delegate  a SharePoint OOTB workflow Task item.

We were able to approve,Reject the status of the OOTB SharePoint Workflow programmatically,but we are stuck when we try to to delegate(Assign somebody else) the workflow task & then the assigned person should complete the workflow(Approve/Reject).

any help would be highly appreciated.

Thanks,
Shahzad Khan