In Structural Modeler, the section picker could be opened from a VBA application by calling tfsecmgr_openSectionPicker.
To call this, you would need to add the following line to your application:
Private Declare Function tfsecmgr_openSectionPicker Lib "triforma.dll" Alias "?tfsecmgr_openSectionPicker@@YGHPAD@Z" (ByVal sectionName As String) As Boolean
If you are trying to run that same application in AECOsim Building Designer, you will find that it no longer works because the DLL has changed.
You can replace the line with:
Private Declare Function tfsecmgr_openSectionPicker Lib "blddesigner.dll" Alias "?tfsecmgr_openSectionPicker@@YGHPAD@Z" (ByVal SectionName As String) As Boolean