I don't know CATIA V5 and then CAA programming.
But, I know well VBA in other applications. Just an example, calling from VBscript a VBA subroutine recorded as a macro in a EXCEL sheet :
' Launch EXCEL and get the corresponding application object
Set ObjScript = CreateObject("Excel.Application"

' If you want to see EXCEL openned
ObjScript.Visible = True
' Loading of the workbook containing the macro
Call ObjScript.workbooks.open("D:\TRY.xls"

' Calling of the subroutine. I suppose one integer argument is expected
call objscript.run("TRY.xls!Feuil1.MyMacro",15)
' The subroutine is completed then I quit EXCEL
call ObjScript.quit
This code was tested and it is OK.
I'm not sure you can do this in the other direction, i.e. call and use of an VBscript object from VBA. I think you can only launch a VB script from VBA by using "shell" or "appactivate" function.
But I suppose you can use this principles for calling between to VBA.