SCCM 2012 - Force Logoff to start deployment of application...

Why not just create a Task Sequence with a Restart as the first part of the sequence.
If that does not work. You can create a Task Sequence that run Shutdown.exe /L /C "Please save all work. Your machine will logoff in 5 minutes. Do not login for 10 mins .  Your machine is being updated........" /T 300

Then schedule the next task.

I like the restart method better.

Could you disable their logon hours until your update has completed?

Here's one way
https://richardspowershellblog.wordpress.com/2012/01/26/setting-a-users-logon-hours/

Or, Lock Out their account in AD?

thank you both for your responses, DanCh99, I don't think your option is a viable one in our situation, just complicates the process,
yo_bee, someone else suggested I look into the task sequence creation on another forum as well, the problem I have with TS, is that if it crashes, it doesn't recover well as can leave us in a worse off state,
Personally, I think we need to get WOL enabled at both SCCM/workstation BIOS layer, and Network switches, this will allow us to get a better deployment success rate when we push on a Sunday, the percentage of users who take thier devices home is small, so we will have to manage that when they connect to the network come Monday morning, expectation from users and management is, that everything must happen within 5 seconds when it comes to SCCM, which we know is not the case.

Either way you will need to create a task sequence to guaranty that the computer is at a logon screen

is it an MSI or and EXE that you are trying to execute?

If it is an MSI you might be better off using GPO to push at boot up.
This will insure that the user is not on during.

You can push out a Scheduled Task to reboot the users computer at some early morning time Sunday into Monday.

At that time when they reboot they will get the publish MSI from GPO.  Users that are off over the weekend will just get the publish msi during their startup on Monday morning.

This removes SCCM out of the mix completely

there is already a scheduled task to reboot workstations at 3am on a Sunday morning,
the issue comes in with users who don't leave thier machines powered on to facilitate the install on the Sunday, the monday morning they come in, as soon as they start up thier machines they immediatly launch the application (which is still the old version) and these are our problem machines/users that we trying get upgraded

So that is why I recommended the restart with the GPO publish and assigned MSI at startup.
The computer will not get to the Ctrl + Alt + Del until the install is computer.

Are you familiar with pushing msi's via GPO?

thanks, I'd prefer to want to stick with SCCM, it's an MSI we deploying, but there are some pre-requisites etc that it checks for

the previous deployment solution we used CA - DSM, had the abilty to lock screen at logon screen to allow install to complete,
Clearly SCCM doesn't have any such ability,

there doesn't appear to be an easy way of achieving what I asked for