I've got a pretty good idea that this is a PLC-5 we're talking about...
The I/O config in RSLogix5 is entirely optional. It's quite convenient, but the program will run just fine without it. It just means that block transfers have to be set up by hand just like we used to do it back in the old days with 6200 software.
The good news is, that if you enter the required data into the I/O config, then the setup button will work. When you enter the module in the I/O config (say for example a 1771-IFE) you will get a popup asking for the following information:
BTR Control
BTW Control
Input Data
Output Data
Enter the values from the BTW & BTR instructions, and the setup button should start working.
Good luck,
*DO* follow Ron's advice and read the reccomended thread. You definitely want to answer "Yes" to keep the existing configuration data.