wiki htaccess page

I'm trying to refresh my memory on setting up custom error pages. I have made the pages, 404.html, and I think I need to put a line in .htaccess for each relevant directory.

Searching the Wiki for "error page" finds what I think is the page I need to view:

http://wiki.dreamhost.com/.htaccess

However, clicking on that gets me

Forbidden.html
There is currently no text in this page, you can search for this page title in other pages or edit this page.

which, I guess, means that someone wrote a nice page and named it .htacess (no dot might have been a good idea!) and then it's been replaced by a real .htacess page OR the wiki program makes .files forbidden.

So: can anyone tell me the line that goes in .htaccess to redirect 404 and other server errors?

Does anyone know how to fix the wiki to display the htaccess page?

http://wiki.dreamhost.com/index.php/.htaccess

.......

I have been told by DH that some antivirus software especially Norton will block that page. I have confirmed this as temporarily disabling Norton will allow the page to display.
Silk

My website

Thanks - it's weird, the links in my search results don't have the index.php bit.