I'm using the rig this way:
guitar goes directly to the input of the mesa boogie triaxis preamp.
The rocktron chamaleon is connected to the effects loop of the triaxis(send & return). so the the guitar signal enters through the input of the triaxis, passes trough the chamaleon and gets out to the output jack.
There, the processed signal goes to the Mesa Bogiee Siml 2:90 power amp.Then it sounds in the 4x12cabinet.

Thanks!!