AB-test : test/track for clicks on a link

Hi,

We are using AB-test and trying to test the styling on a specific link. we have setup the test properly and it is working.
But the page the link refers to is outside the MODX installation so i can’t put in the [[!sabConversion]] there.
So how can we track the clicks on a link with AB-test to see what styling is most effective?

RDG