That "isPageView" is really determined by the type of beacon that you send: a Pageview beacon or a Custom/Download/Exit Link beacon. So you can certainly set your eVar's value based on the beacon that you are using to send the data to AA.
On the other hand, I'm not sure why you'd want to do this. In Adobe Analytics' Analysis Workspace, you can drag in these metrics: Page Views, Custom Link Instances, Download Link Instances, Exit Link Instances, and AA will happily report the numbers for each metric.