if you're just getting 2 tracks down into the line-in (analog 4 track) then audacity is all you need.
if your 4 track is usb & you can preserve the tracks it's beyond my expertise.
maybe
goldwave? has a free trial and its cheap with the exchange rate.
ive also used
kristal audio for laying multiple tracks. its ultra-cheap, and by that i mean free.
but vallhollaing & others can give better advice on this.