Cameron,
The answer to this question is as follows:
"You can only get to them with a policy, and you can't schedule an update as a policy. You can schedule a script as a policy, so if the change is something minor like a registry flag, you can push it out in the form of a batch file. For a major change, you have to save a self-contained .exe of the agent file and push that as a policy."
Quote: http://community.landesk.com/support/message/7025#7025
Therefore depending on the level of change you are making to your client then, it will depend on whether you are able to use a script or not to resolve this issue. Otherwise as suggested you will need to make a self-contained package and supply that to your targets via the policy.
I hope the above statements allow you to get to a resolution and progress your issues, I know that they are not exactly what you wanted to see, but it should clarify the situation for you.
If you still have concerns about this then I would suggest getting in touch with Support,
Regards,
Stephen