Route The Line/Headphone Out To The Input

Hi. I need to run some acoustic measurements using Room EQ Wizard with an omnidirectional microphone and one of the calibration steps is to route the output from the soundcard's line or headphone back into the inputs. Is it possible to do this in software rather than having to run a physical cable? Discussed here: http://www.roomeqwizard.com/help/help_en-GB/html/calsoundcard.html#calmeasure

Thanks