Yeah, I got something like that going for AAM - you can change users, but not add or delete or modify COSs for them.
Lots of playing in "Groups and Roles".
In Groups, I associate only the voicemails the user is to access in a group - say "US Voicemails" and only include MSS servers in the US
In Roles, I create a new role, - USVMAdmin. I then add a mapping to group "US Voicemails", and ultimately you get a series of checkboxes where I can permit certain things. I've got some profiles setup to permit only editing phones and mailboxes, but they're system-wide the particular systems I've applied them to
I'm looking through the administration guide for 6.3, page 171
I must admit, I've got the same problem you do! It goes through just like 6.2 and I've followed most of it through, but I don't see a "range" field either.
I suspect perhaps this is a planned feature that creeped into documentation but not the GA product...I'll try to update when my support ticket is addressed.