Here's how to create your own Print File service, so you can easily print the selected file. Open Automator and choose Service from the initial dialog. In the search box on the left, search for Print Finder Items, then drag that action into the right-hand frame.

At the top of the right-hand frame, set the first drop-down to files or folders, then save your Service as Print File (or whatever you want to call it). You can now print by selecting a file and choosing Service » Print File, and you can optionally assign a keyboard shortcut using the Keyboard Shortcuts tab of the Keyboard System Preferences panel.

You can also download the finished Service, if you prefer.

[robg adds: I'd suggest setting the second drop-down menu to Finder, as that's where it makes sense to be selecting files for printing. I tested this (by building it myself, not by using the downloaded file), and it works -- note, though, that the file will print immediately, without any confirmation or settings panel, nor with any ability to select which printer will be used.]