Working with Chris Mattson, I think I've found a compatible solution for using ScriptBasic embedded for internal BOI scripting.
When using Custom Office to create your script, write it in ScriptBasic COM and save the script with a .sb file type attribute. This is simular to using WSH .js scripts.
This will embed ScriptBasic as the scripting engine instead of instantiating MSScriptControl.ScriptControl.
I will post an example after doing some testing.