You should be fine, the XG0, XG1, and XG2 are the primary, secondary, and tertiary chains respectively. **IDEALLY**, you would have the first two chains (XG0 and XG1) 90degrees polarized, with the third (XG2) on the 45deg element.
For Omni's, you would have:
* XG0 - Vertical
* XG1 - Horizonal
* XG2 - Vertical
For the D608, when you look at the back you should see a -45, V, and +45:
* XG0 - -45 or +45 (so long as XG0 and XG1 are 90deg polarized)
* XG1 - -45 or +45 (so long as XG0 and XG1 are 90deg polarized)
* XG2 - Vertical
Hope that helps