In VEMSTune look at all the analog voltages, choose one that is 5v constantly with nothing connected, you´ll see it on the gauges.
Then wire in a ON/OFF switch that has one wire connected to an available 5v pulled analog channel and the other side is connected to ground.
When you turn the switch to map 2 or B the voltage should go 0v
Base setup - Config switching
Select the channel you have wired the switch to and select MCP Input.
Then select File - Upload Advanced and select A and B and select your latest config. What you have done is moved the current config to both sides. The ecu will stay in Config A as it´s called. When you flip the switch it will go to Config B.
Now you can tune Config B as you want, and at anytime if you want to upload only a map to Config B side you select File - Upload Advanced and select only B side. remember you must keep the switch the same otherwise you might get continous config changing.