Someone gave me the sudo command in another thread of mine. Thanks for your tips anyways.
I still think an Automator workflow will get this done and also have the benefit of being able to save the workflow to any easily accessible space to allow double clicking. You can customize the workflows to set specific times, force times, detect idle times, etc...
All without requiring an administrator password.
For example, I just setup an Automator workflow to sleep my MacBook Air after 10 minutes of inactivity and saved it to my desktop. System Preferences settings are held until you double click that Automator workflow. Now, after 10 minutes of inactivity, the Mac will sleep. Upon wake up, System Preferences settings are active again. Essentially giving you two different usable times. Want 3? Make another Automator workflow.
Open Automator.
Select "Application" as the type.
In the search bar, search "Idle".
Drag "Get Idle Time" into the workflow area on the right.
In the "Get Idle Time" action, select "After" and set it to desired time.
Back in the search, search "Sleep".
Find "Put Computer to Sleep".
Drag that into the workflow area.
Save the workflow wherever you want with whatever name you want.
Double click it to enable that workflow.
Should do what you're after and not require an administrator password.