there's no "easy" way to do this. You will have to get some leads or plugs that convert your tape player's "rec out" RCA plugs to 1/4" inputs for the VF80.
then, the hard part....you can only record 2 tracks at once on the VF80, so you will have to pan track 1 from the tape to the LEFT and that will be automatically assigned to track 1 on the VF80, pan track 2 RIGHT and it will go to track 2 on the VF80.
record those two.
then set up the same process for tape tracks 3 and 4...being panned so they end up on tracks 3 and 4 on the VF80. Record these as closely as you can in alignment to tracks 1 and 2. You will then have to cut and paste tracks 3 and 4 until they line up with the first two!
The only other way is to mix your tracks down to a two track stereo or straight into the VF80 as two tracks as you go.