Hello Lockedown,
SSL won't record a mix straight into the computer via the usb cable.
It will record through either input 1, 2, or mic but not a mix.
To record a mix you need to run a separate out of your mixer either into a recording device or back into your computer via the 1/8' line input and use a separate recording program such as Soundforge, Peak, or Audacity.
You will find the recordings you made via input 1, 2, or mic in the 'Recording' folder inside the 'Scratch LIVE' folder on your internal drive.
Taken from the manual:
Recording from a microphone
Scratch LIVE allows you to record from the Mic Input and
scratch it immediately as if it were on vinyl. Use the mic input level indicator on the screen and the MIC GAIN control on the SL 1 box to adjust the mic recording level.
Click on the downward pointing triangle and set the input to mic, and click on the red mic button to start recording.
Click the mic button again to stop recording.
The mic button flashes during recording.
To play the recording, type in a name for the recording and
click the save button. The recording is automatically placed
in a crate named Recorded.
If that crate does not already exist, it will be created.
To start a new recording without saving, simply
re-click the mic rec button.
Recordings can be loaded onto the decks, renamed and managed
like other files. Recordings are saved in ‘My DocumentsMy
MusicScratchLIVERecording’ on a PC, and ~/Music/ScratchLIVE/
Recording/ on a Mac. Recordings are saved as 16-bit mono AIFF
files. To quickly load a recording on to a deck without saving it first, click the mic button to start the recording, and then use the short cut keys shift  or shift  to load the track.
If you load the recording in this way, the recording will not be added to the library, and will be discarded on exit. To keep the recording, copy the file found in ‘My documentsMy MusicScratchLIVERecording temp’ on PC and in ‘~/Music/ScratchLIVE/Recording temp on a Mac.
Tip: Use keyboard shortcut ctrl-n to start a new microphone
recording.
Sampling from vinyl
You can use the SL 1 interface to sample from vinyl or any other sound source. If you click on the triangle next to the mic record button, you'll see that you can select inputs 1 and 2. Select one of these, and you'll see a input level adjustment knob appear to the right of the level indicators. This boosts or attenuates the input signal up to 12 dB. The recordings are in the same format and saved to the same place as mic recordings. On a PC this is in ‘My DocumentsMy MusicScratchLIVERecording.
On a Mac this is ~/Music/ScratchLIVE/Recording/.
The file is saved as a 44.1Khz 16-bit stereo AIFF file.
The input select in the setup screen (line or phone) determines whether or not the phono preamp is used.
Tip: remember that ctrl-n turns recording on and off, and
that you can load a recording without saving it using shift 
or shift . Drop the needle into a loud part of the track, and
record a few seconds, and then shift  or shift  to load it on to the virtual deck.
This way you can double check your levels.
If the virtual deck is set to int mode, and is unloaded, the
input record level is sent to the virtual deck's higher resolution stereo meters.
E.g., if you're recording from input 2, set the right
virtual deck to int, eject the track if there is one loaded, and the virtual deck’s meters will show the signal coming into input 2.