In my version of firefox in Windows, I use the "Manage Bookmarks" and then export bookmarks.
This saves a HTML file with all your bookmarks on one page.
I just copy this to my C3100 and open this page in Netfront.
All the links are clickable in Netfront. I don't use Opera.
Once you have used this page in Netfront, you can save it as a bookmark, and it will be listed in the bookmarks area of Netfront.