I'm working on a project which has thousands of lines of Coldfusion written with tabs. (Now's not the time to start that argument again!) I'm obviously not keen on throwing 2 spaces in the mix for indentation, so I looked up a way to override indentation for .cfm and .cfc files only.
It sounds like there are a few different ways to do this, but the easiest way is adding this line at the bottom of your ~/.vimrc/.
autocmd FileType cfml setlocal tabstop=8 shiftwidth=4 softtabstop=4 noexpandtab
You may want to run :h tabstop in vim and read the notes about best practices for indentation. I did. :)
Here's the ubiquitious SO answer, and here's the Coldfusion syntax highlighter vim plugin I'm using.