In Wizstyle.vcx (wizards directory)-> txtbtns, check the method setallprop, which is a general purpose routine to enable/disable items, It can be used after few modifications,

One line I can tell you which I modified:-

Original
CASE ATC(m.oControlParent.Controls[m.i].BaseClass,"CheckBox,TextBox,OleBoundControl") #

I changed it to

CASE ATC(m.oControlParent.Controls[m.i].BaseClass,"ComboBox,CheckBox,TextBox,OleBoundControl") #

to include combo boxes also.

Depending on the requirement it can be modified and made as a general purpose routine. Hope this helps somebody !!