If you have a bypass kit installed, there will be a pipe on the back of the hot water tank between the cold input and the hot output line. There are several ways the bypass is done, with one three way valve in the cold line and a check valve between the tee and the tank hot output, two three way valves connecting the bypass pipe, or three valves and tees (the bypass pipe is connected by tees, and there is a valve in between the tank outlets and the tees and one it the bypass line.
Check the back of your tank to see if you have a bypass kit installed and tell us how it is connected and we can tell you how to set the valves.
Here's a picture of one set up:
Here is a clearer picture of a one valve set up from JohnB:
2004 Dodge Ram 2500 Club Cab 4x4 CTD
2007 Sunline Solaris T-276-SR: Misty Blue/Cherry
2001 Dodge Ram 1500 Reg Cab 4x4 OFF-ROAD