Those sound like mutually exclusive options, so I would suggest using radio buttons or regular buttons instead of check boxes. It also sounds like you're trying to set the initial state, and then allow an end user to view and possibly change the features selected by the initial page. If that's correct, I would suggest putting actions on those (regular or radio) buttons that do one or more:
Code:
{SetProperty FEATURE[Feat1].actionState=install}
{SetProperty FEATURE[Feat2].actionState=}
{SetProperty FEATURE[Feat3].actionState=}
or
Code:
{SetProperty FEATURE[Feat1].actionState=}
{SetProperty FEATURE[Feat2].actionState=install}
{SetProperty FEATURE[Feat3].actionState=install}
respectively. Just append them all together on the Action for the button, possibly followed by a {SetActivePage nextPage}.
Michael Urman - Staff Software Engineer - Flexera Software: InstallShield Team