Is it possible to have an error 404 page without a domain? I don't think you can, but im not sure.

I actually have a .tk domain. would it work with that?

Do you mean a custom 404 page?

yeah, soz

I've never made them before, but this page might help:

http://www.404lounge.net/index.php?content=custom&css=

The host just needs to support .htaccess, 99% of free hosts dont so if you are on a free host chances are you cant have one.

I can tell you freeservers does. They are a pretty good free host except that you have to have ads on every page: pop-up, or somewhere on the page, and you get emails asking you to upgrade.