AFAIK it's a line-level output, which would go into the blue line input minijack on a typical sound card (pink is microphone input). At that point all you need is something like Room EQ Wizard (the "REW" everyone talks about) and you're ready to start making undecipherable graphs.

I found an online manual link which seems to match what I remember about my meter:

http://www.ko4bb.com/Manuals/08%29_Misc_...r_with_Mods.pdf

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8