In practice shove the faders up on just two faders, 1-5 or 2-6 or any combination, but you will need to experiment which one gives best signal to noise and no crosstalk. If the 2track cassette is recorded on both sides, you will struggle as the alignment means some tracks will 'collect' the backwards audio from the other side. You then load that into your DAW and make it half the speed. I never made it work very well when I had one - I could never get rid of the track on the other side.
To be honest, just beg, borrow or buy a proper stereo one, with Dolby, or whatever noise reduction your 2 track has - too much faffing around to be practical. You also have to make decisions based on the squeaky sound of the music playing at double speed, so sometimes when you fix that, you end up with a rotten sounding end product.