TeX hyphenation patterns

Does anyone have a clue on how these hyphenation patterns in Tex are built created and how they work?

For instance, there is a word in Dutch "Praktijkuren" that's being hyphened to "Praktij-kuren" while it should be "Praktijk-uren". The only Dutch hyphen pattern file that exists, does not contain the correct pattern for this word. So I need to add it, but how?!

There are some programs to make this magic happen, but only for Windows or Linux, and I have only access to Mac's.

Any help would be appreciated.