Well the boys at Mitchell be lying to you.

If you head over to http://www.sysinternals.com you'll find some nice little snooping tools that wil help you to locate and find what the programs are accessing and what methods are used and you can then modify those permissons to include a group of your choosing with the specific rights.

This is a bit of an advanced method, but it can be done.

As for a time being applied to the SHARE, not that I'm aware of.