I just had to try programmed binding, Karri. 
And I'm glad I did because I learned some things I didn't know. The main thing is I learned that it will not work in my case because it does not process until after the work item is completed.
I did as Ronen suggested and now I have 1 step with the task which takes the user to MM02. Let's say they execute the task and change the MRP Controller. When Save is pressed, it automatically shows a screen with the task description (old MRP Controller) asking if the user wants to Complete the Work Item or Cancel. This is where I need to have the new value for the MRP Controller. With programmed binding I was able to change the workflow container but it is only good for the next step in the process - not here.
Do you think it is possible to use a program exit to change the container value BEFORE the screen pops up to confirm end of processing?