How to number the ToC?

I need to give a Roman number to the ToC. So basically, I want the ToC to internally use \chapter instead of \chapter*. Is there any way to do that?

You could temporarily change the meaning of \chapter*:
\let\stdchapter\chapter

I used \contentsname for the optional argument to \stdchapter because the argument #1 might contain mark commands for the headings, for example \@mkboth. That's no problem for the starred command, but if you would use an unstarred command without the optional argument, the mark command would be put into the TOC line as well.