it is possible to use Run Client Task Now to create a new McAfee Agent Update task to apply all or selected signature and service pack updates to machines, however with only the above permission "McAfee Agent: View and change task settings" it is not possible to create a new deployment task (at least not under 5.1 and I believe this was the same under 4.6.6). You can select the Product, "McAfee Agent", Task Type, "Product Deployment", but if you then select "Create New Task" under Task Name to install or remove products then "Products and components" shows "no permissions"."
You need the "Master Repository - View Packages" permission to be able to deploy or remove packages to/from clients.
I have just spent a lot of time testing these settings to verify under 5.1, since I needed to be able to delegate the ability to repush the agent or tasks by remote sites' helpdesk personnel, without allowing them to modify existing tasks.
One important thing I have noticed whilst using "Run Client Task Now" - never try to run more than one task at the same time, ie. never try to deploy a new version of more than one product, etc. My experience over the last couple of years has shown these to fail, whereas I accidentally discovered that if I only added or removed one McAfee software product it worked very well. With updates you can select more than one. Maybe somebody else has had different experiences but my tasks always failed if more than one component was selected.
PS I have been managing ePO for my company (over 5000 clients) for over 15 years, since the very first version.