Thanks for the replies everyone! Good to see you again audioguru. It has been a while since i've been on the boards.
I've hooked it up as per recommendations and unfortunately the outcome was rather disappointing. It would appear that there is TOO MUCH attenuation in the system. With the volume cranked up, i don't get much output.
There is also a rather noticable HPF effect, leaving the lowend/mids very empty.
It would appear that it's back to the FM modulator for now until I can figure out how to disconnect the tape deck alltogether. Unfortunately it is not just discrete circuitry and not some outputs i can pull low/high to be able to strip out the tape deck portion.
Barring which, I would have to cannibalize the entire tape deck to get things working, which given that this tape deck is the only surviving cassette player in the family, and there might be a old recorded tape that I might need to play back.. someday, i'm hesitant to tear up the tape deck for now.
Any ideas on resistance/values? I've noticed that the other variants of the stereo have an attenuation resistor which the guides say to bridge over to cut out the attenuation.