For those searching it, there’s already a direct link to the expansion patcher. You can dig here to find it:
http://mythic.fileburst.com/downloads/

I’m already at 27% with Bittorrent and my powerful dialup, so I’m not going to restart from zero even if I probably could finish faster.

They are keeping changing the file name, that’s why I said you’ll have to hunt for it. Right now the name is:
figure_this_name_out_h4x0rz_catacombs_to_darkness_setup.exe

If you are unsure about the validity of the file you could always download a chunk and then load it in bittorrent to verify it. The best feature of that clunky program is that it verifies and repair the files automatically.

EDIT: Both links died long ago. There’s also a rumor about WoW patch being released and I still have to download Rag Doll Kung Fu. Too much goodies these days…