UK spelling dictionary - teach OS X *all* -ize spellings

The British spelling dictionary in OS X is customized to UK spellings, a very useful feature. However, the designers have made the unfortunate choice of only listing -ise endings for words such as advertise, customise, etc. Many Brits, such as myself, prefer the -ize spelling. In Lion, auto correct keeps changing all my -ize spellings to -ise. Not what I want! Can any of you suggest a clever way (perhaps a perl script?) to quickly add all -ize variants of corresponding -ise spellings to the local dictionary? Note: the suggestion "switch to US spellings" is not acceptable!