Sure, very possible. Depends on your sound card though. Does it have more than 2 inputs? Does your tape multitracker have seperate outs for each track? If it's yes to both of the above, should be a breeze.
If your soundcard only has 2 inputs, all is not lost. Send out the L/R stereo 2 tracks at a time and sync them up. Could be tricky, but not impossible.
Emeric