I have checked the signal flow chart of your mixer, and I think, this way should work and would be a better (still not superb) way to connect things (to make the setup more clear I made the letters for connections and switches bold. All the rest is explaining why and what):

Send mic/instr thru "FX send" or from the "CD/Tape output L/R" to your computer. FX send is post fader so need to keep the channel's volume also open if you decide to use FX send. The signal comes back thru the computer, which means you cannot listen (during the recording) to the ingoing signal, but to the returning recording signal only. You can do the gainsetting of your mixer visually with the clip-LED and on your ears from the returning signal of your computer or release the CD/Tape to CTRL button, which breaks your computeroutput connection and make your input signal come via the stereobusses into your controlroom section..

To prevent the signal of the inputsignal also to go to the mainmix outputs you should beware that the CD/"Tape to ctrl" button stays pressed. (which breaks the internal connection from the stereo bus to ctrl out)

Route the computer back into the "CD/tape input L/R. The switch for "CD/tape to CTRL" pressed (recording mode), or released (input signal monitoring). The switch for "CD/Tape to mix" Should ALWAYS be released. (this prevents the signal to go back to the stereobuss and been send to the computer again, so it prevents the signal to cause feedback)

As far as I can see there will be no feedback this way, since the control out either receives the incoming channel or the CD/Tape (return from computer). The "CD/tape to CTRL" switch eliminates the signal from one of those. So pressed you hear the computersignal, released the ingoing signal.

Now you got yourself a stereo "tape"return. So that means you can keep the stereo mix in your computer during recording.