How to validate dependent settings in general options?

[FractalizeR]

Hello.

Does anybody know, how do I insert arbitrary HTML code instead of some setting at /admincp/options.php?do=options page? I need to give the user a possibility to validate the whole settings group. This can be done by adding a button to settings page (calling validation script) or by executing custom code on saving these settings.

I cannot use option validation PHP code, because some settings must be validated in a group only.