Reply to Recording w/ audio 4 and traktor pro?

Hey I bought traktor scratch duo and will be upgrading to pro shortly. However upgrading only gets you the software and not the audio 8. so my question is how will I record using scratch pro, the audio 4, and an external mixer? I also have a crap mixer that only has the line/phono inputs and one output. So I dont know what to do exactly besides buy a new mixer and the audio 8....