How do I insert and outboard processor in the signal path on a Integra DTR 7.2?

Since you don't have a  preamp out - main in, I don't think you can.

Through trial and error , this is what I came up with;
Tape out to input of EQ EQ output to Tape Input.
Select recording input then select tape as source.
That seemed to work, rather clumsy though.
I thought I could just go from 7.1 Pre-Out to 
Multi-Channel Input. But what do I know?

I think these units have multiple zones too, right? You could use the pre outs back to another input.