Off the cuff...
The Ross 4 x 4 has 4 (Mic/Line/Tape) inputs, 4 (assign) busses & 4 (tape) tracks, enabling you to assign each input to any of 4 tracks. Inputs would be switchable between "Mic/Line Input" and "Tape" (or Off). In general, (Assign) Buss 1/3 would be correlated with PAN-Left on the mixer channel, and Buss 2/4 associated with PAN-Right.
Let's say you've successfully recorded onto Tracks 1-3, and want to bounce these tracks to Track 4.
Set the channels 1-3 to play back from TAPE, assign channels 1-3 to Buss 4, and pan channels 1-3 either in the center or hard-right,... mix to taste,... and when you're satisfied with balance record all 3 tape tracks to track 4 thru the internal mixer. You may also record one live part down to track 4 simultaneously as the bounce-dub.
By using this bounce technique (including laying a live part down during the bounce) successively to each track, you may get 4 parts on Track 4, 3 parts on track 3, 2 parts on track 2 and 1 part on the remaining track,... a total of 10 parts on 4 tracks of tape. Although this maximum bounce may sound glamourous to get 10 parts down to tape, the fidelity will suffer a bit in the exchange, and by virtue of this "collapse" bounce technique, all the original source tracks going into the bounce will be overwritten during the process. Giving great care to track bounce technique can give acceptable results and may help extend the limits of 4-track recording. However, the un-bounced track is always better than a bounced-track. If you try to be clever about what parts to mix and bounce, and try to keep it to a minimum, with practice should yield very acceptable recordings.
However, I think if your productions always involve bouncing you may be benefitted by upgrading your recorder to more tracks. F/I, I'd choose a Tascam cassette 8-track over a cassette 4-track, if bouncing figured large into my 4-track productions. Maybe OT.