I've been in a similar job before, as the lone tech guy, and one small step that really helped me was to require that all work requests be sent by email. I put a sign on the door to my office/server room that said "Verbal requests will be cheerfully forgotten. Mail to tech@company.com".
That won't get rid of everything that comes in your door, and you may find yourself reduced to sending the email yourself, for something your boss walked in and wanted you to do. And it won't stop the "OMG the network is down" freak-outs, either.
On the other hand, it will hopefully reduce your walk-in interruptions, and it will give you more of a record of the work you're doing. Bosses who don't understand anything beyond rebooting can see how many work requests you're handling in a day, to tell how busy you are. Ideally, you can have the 'tech@' alias CC your boss and other crucial managers, at least at the start, so they can see how much you're doing.
I use this technique as well, an additional benefit is the record of requests from specific individuals: "Hey boss, check out how many times X has emailed me asking to reboot his 'workstation' for him."
That won't get rid of everything that comes in your door, and you may find yourself reduced to sending the email yourself, for something your boss walked in and wanted you to do. And it won't stop the "OMG the network is down" freak-outs, either.
On the other hand, it will hopefully reduce your walk-in interruptions, and it will give you more of a record of the work you're doing. Bosses who don't understand anything beyond rebooting can see how many work requests you're handling in a day, to tell how busy you are. Ideally, you can have the 'tech@' alias CC your boss and other crucial managers, at least at the start, so they can see how much you're doing.