User Decision in a Module Pool

Hello Guys,

I am relatively new to SAP workflows. I am implementing a solution here and I have mixed feelings about the design. I would love to hear some advice on how to proceed or some reassurance that I am going in the right path.

Requirement:

1. If a Requeust (say Material Creation)  is created by the Initiator in my Custom Module Pool program, the workflow is triggered and sent to the Approver.
2. The Approver should View the Request by executing the workitem from his Inbox which will in-turn call the Module Pool Program.
3. From there the approver will have two options either to Approve or Send Back.
4. I have designed my workflow like this...

          View Request  (Activity)

                  |

          Aprrove / Reject  (User Decision)

   5.  I am marking the 'View Request' activty as complete from my Dialog Program so as to make the workflow come to the User Decision step so that I can pick one and execute form the Module Pool. I have a bad feeling that it might not be a standardized method. If not, then how shall I proceed.??