Launch Chrome from within Excel on a MAC?

Hi,

Using Windows 7/Excel 2010 I use the shell command to launch Chrome when a command button is clicked

Shell ("C:\Users\" & UserName.Text & "\AppData\Local\Google\Chrome\Application\Chrome.exe -url " & WebsiteDomain.Text)

A colleague needs the same functionality but he uses an Apple Mac. Does anyone please know the equivalent format for launching Chrome on a Mac using Excel 2010? I've never used a Mac in my life and have no clue how to even find the location of chrome.exe (or even if it uses .exe)

Thanks

ChainsawDR