Form code is launched from events on a form/report or from events on controls that live on the form or report. Most of the initialization of a Wizard is started from the OnOpen event of the main Wizard form. To do this, set the "OnOpen" property of the form to "[Event Procedure]," as shown below.
All that is left to hook the CBF to the Wizard is to open the form, so we add the following line. You will notice that we have opened the form as a dialog box, which is necessary in order to halt execution of the entry point until the form closes.
DoCmd OpenForm "zwfrmSubform", , , , , A_DIALOG