Ok, I tried it, but something goes wrong. I think the hyphen dic is too large for Kobo (855,2 k).
I used this the one from this OpenOffice extension:
http://extensions.openoffice.org/en/...ictionary-pack
I tried on a previously opened book, it does the hyphenation, altough the text looks better without the hyphen-dic installed, and the book fails when reading, Kobo show a blank page when I opened the book, then i tried to jump to the chapter where it was last open, it loaded the page, but i could only turn one page to the right, then Kobo exit the book and told me i have finished the book. The same happanes when i try to turn back one page, or it does not turn the page at all. I can't even jump to pages in the menu. After removing the hyphen dic file, it's back to normal. Wierd.