In Pega 6.3, you can achieve the requested alternate row coloring through Grid style set as Spreadsheet.
Refer the Grid example from OOTB(Out of the box) UI Gallery. Pega button >> User Interface >> UI Gallery >> Grid. Below is the screenshot for your quick reference:
In Pega 7.2.2, for OOTB Grid example (Designer Studio >> User Interface >> UI Gallery >> Grid, set the style as 'Default' and Container format as 'Default'. Test it by modifying the grid in the pzUIGalleryBasicGrid rule through private edit. In the custom skin rule, check the option 'Enable row banding options(zebra striping)'(if this is not checked) for a specific format under Trees & Grid component style, save it through private edit. You will see the desired outcome.