TLKTools is a higly configurable command-line TLK<->XML conversion tool, TLK patcher, TLK translation helper, and much more.
The limits of what you can do with it are really loose; take a look at sample.xml for a preview of its capabilities.
Available both for Windows and Linux (but should compile on MacOS-X, too).
Updates:
2013-01-26: Fixed broken link (Thanks ShadoOow!) - Rolo