Change "Startup object" of the current project via Add-In

Hello all!

I'm developing a VB6 add-in that should make several changes on the current project.
Now I'm stuck on modifying "startup object".

1) There is no such property in VBIDE.VBE.ActiveVBProject.
2) VBIDE.VBE.ActiveVBProject has functions Read/WriteProperty. But the needed property "Startup" in vbp-file has no section and cannot be readed.

Has anyone any ideas?

Thanks in advance