Question: My system is Windows Server 2008 R2 with IIS 7.5. I need to run a site which is allowed to do some administrative tasks. I have created an AD user account and added it to all the required groups. The site's application pool runs with custom identity set to this AD account. This works, however some tasks fail with 'Access is denied'. I have found that it was caused by UAC (with UAC disabled everything works ok).

So my question is - is it possible to run an application pool in elevated mode without globally disabling UAC? Possibly just disabling UAC just for this one account.

Answer: 
I would spend the time you have writing a document that gives a good overview of the big picture with all the major components for whatever their area is. Then they can use it as a reference, and an overview of what they may need to learn. So for example, if you have big cluster setups draw pictures of those. If they are network admins at least put together a decent diagram of the company's network. 

From there, I would start documenting anything that is unusual about the environment, followed by anything that is particularly advanced or complicated.

If these are lower level positions where they will be doing mostly repetitive tasks then the howtos make sense to me, but if they are more advanced positions then the big picture combined with the unusal/complex documentation I described makes the most sense.
I set up a wiki at our office to capture snippets of knowledge as the devs had time to write stuff. The boss was only willing to allow "full and complete documents" so he wanted sharepoint instead. Since no dev had time to do "dull and complete docs" there were none written, and as the PHB banned the wiki, we're back to where we were a couple years ago.