Doing a podcast and here is what I want to do. So I have three sources, two from an Alesia Multimix 8 USB FX and one from Skype. I want to record each of these simultaneously onto different tracks in Sonar Artist. Right now when I do it, they all record on all three tracks. I need to separate them.

Hi. From Akai's description on their web page: "The MultiMix 8 USB FX enables bidirectional stereo signal".
It seems you can only have a stereo (maybe two mono) signal(s) into SONAR. 
Do not know if by using MME or WDM/KS drivers, you could use both your mixer and internal sound card. Others might know.
All the best.

Per online specs, the Multimix 8 has 8 analog inputs to its analog mixer section but only one stereo digital interface input to the DAW via USB. If you pan the two analog inputs hard left and right, you can record them to two mono tracks with inputs set to left and right channels of the stereo interface input.
 
It's not clear how you're getting the Skype signal into the mix, but, unfortunately, you're not going to be able to record 3 inputs simultaneously with only one stereo input to the DAW from the interface in any case.