The reliability of on-screen color display is not such, that you'll really want to be plucking PMS colors from a monitor.
If you must, you can make two swatches side-by-side, one with your CMYK color, and one with changing PMS shades until you find a match.
I do believe there's a plugin or script for reverse swatching, but I don't remember now where I saw it. Maybe do a search.
Illustrator does not have a native tool to do this, nor do I think it should based on my initial statement.
HTH
Bert