[Coco] How can you make permanent directory changes in OS-9 ml programs?

[Robert Gault]

I need to use I$ChgDir in an OS-9 ml program where the changes continue to exist 
after leaving the program. The only method I found that works is to exit the 
program with F$Chain where the chained program is Shell. That of course leaves 
the old shell running.

Is there a method that either kills the old shell or returns to the old shell 
with new paths intact?