He said that in 2005 and hasn't been around much since!

There is a mod-switch program by Vercingetorix here.

I've not tried that but I suspect it is what he was working on. There is also a program called JSME (?) I think which can be used.

If you are making a mod yourself though you should use the built in -mod system see here for discussion. That is actually quite an easy system to set up, though there are important differences between the way it works for RTW and BI.