Start Keyclone and go into Setup and into the Mouse-Map tab.
Under Mouse Action, click youre Xbutton 1 and bind it to F11
Do the same whit Xbutton 2 and bind it to F12
Ingame bind Turn left to F11 And Turn Right to F12


Had some problems myself becuse Xbutton 2 Freezed keclone, fixed it by binding Xbutton 2 to F11 in Setpoint.