Mount point problem

[Jay O'Brien]

I've changed the mount point for devices; i.e., ad0s1g 
was /usr and now I want ad0s1f to mount on boot as /usr. 

I can't seem to get anywhere with disklabel editor in 
single-user mode. It errors out; device busy. When I 
start diskeditor again, mount points are shown as <none>. 

I'm sure I'm overlooking a very basic issue, and I could 
sure use some guidance.

Jay O'Brien
Rio Linda, CA USA