How to get a double-hyphen

I am developing a hyphenator for Basque, and even if I know it would sound weird, for compound words I need them to be double hyphenated when the break point is the hyphen, starting the new line with another hyphen. I mean for example the word "zientzia-gizon" , should become "zientzia-" and in the next line "-gizon".

I searched the forums and I found that in this thread the Brazilian Portuguese behaves this way. Any idea of how to do that?

Thanks!

Greg.