This can be done with a lot of work on your part. I refer you to the tutorial found here. This tutorial explains how to customize the OI to handle UI Messaging doing something similar to what you want to achieve. I recommend reading this tutorial thoroughly and understanding UI Messaging before tackling your situation. Basically, you can change the menu when a user right clicks on a step in the sequence. Then you will have to send different messages based on what they enter.
Also note that at the end of the tutorial there is a link to the finished OI. You could just modify that one if you wanted to or use code from it.
Message Edited by Sam R on 05-04-2006 03:22 PM