Can I install on my own server?

You can use any equation rendering service you like. So long as it adhere to the same protocol.

The original backend code is LaTeXRender from http://www.mayer.dial.pipex.com/tex.htm

On the whole setting all this up is hardly worth hassle for small website like yours. If your a corporation and need the extra power or your installing this on your own internal intranet then thats a different subject. Given the time it'll take us to support this and write the documentation we ask for a much larger donation. However you aren't either of these, so I would focus on the content to the rest of your site first!