No problem all you need to do is get one member of the management team to take this person out for a Liquid Lunch and while they are out of the office walk into his office, cubical whatever with a External HDD and perform the backup with only moving as little as possible. When they return drunk as a skunk he will not realize that things have been moved or think that he is so drunk that he did it himself.
Well that's what I would organize at least you may have other problems where you are with that so you will need something different. It really depends on the person involved here you need to cater to their weakness be that women, booze or whatever I don't know the person or circumstances so I can't say for sure. But just because he is allowed to take it home doesn't mean that he can do as he pleases with it. If he makes changes it can adversely impact on the Companies Security Policy so he may infect the system bring it in, connect it to the domain and then infect the domain. That is a good case a bad case involves infecting the NB and then connecting to the work system and the NB makes a copy of all critical data and when he goes home that data gets sent over the Internet connection to some other place without his knowledge or worse still with his knowledge. The last is the worst thing that can happen as it means that he is working against the wellbeing of the company.
If it isn't deliberate it's stupidity both cost a lot of money to fix up regardless. I suppose you could go in and attack the unit while he's out somewhere and delete something important to the OS so when he restarts it it doesn't boot. He will then run into IT and demand that it gets fixed Immediately and while you are at it you can Clone the Drive before starting to replace the missing file. A dead NB Battery is another good thing to try but you first have to make sure that there are no spares lying around that he could use so that the NB doesn't come into the IT Department.
Really though if Management want a backup they should just tell him to deliver the NB to be Backed up and updated as required by the Company Security Policy.
You could always ask for it under the pretense of adding something new and while you have it Clone/Ghost/Image the drive with whatever you are using to make a Backup. It's not really your call though if Management will not do as they tell others to do it's hardly your place to steal things to follow Company Policy.
[b]If you where to get caught doing this would Management Support you against his complaints?[/b] I'm sure he would be demanding your Immediate Dismissal so is it worht the risk even if you where to have Written Direction to do this. Basically who is more important to the company him or you? Who will cost the company less to get rid of?
I personally would just walk in, in front of him pickup the NB and walk out saying something over my shoulder on the way out about a New AV product or Application whatever is handy and needed.
I hope that is of some assistance but I don't think it will be.
Col