workflow problem

[TCS BISWAJIT DAS]

Hi all.
I have to insert a check condition which will determine agent as per some
conditions..

The workflow is for leave cancellation approval.
the exact scenario is like :
1.    if the leave days are greater than 30 days then the
approver would be the superior of the immidiate             superior of the
requester.
2.    if the leave type is PL then the approver is different than other
leave types.

can anybody show me a way..I'm a new entrant in this workflow world ..