How can I check IE compatibility when I'm developing a website on MacOSX, primarily using Chrome.
I suggest using Wine to install and run the IE versions you need. I am not a Mac user myself but I think you can get a good environment with WineBottler.
You should have a parallels windows install to test IE and Firefox. That will show you exactly what a windows user would see.
I use Parallels & also use Adobe's Browserlab which lets you test virtually all browsers. This is useful as even with a virtual machine you can't test easily all versions of IE, unless you have multiple VMs, which is just too much. Good luck.
Virtual Box(http://www.virtualbox.org/) is a free VM solution from Oracle(formerly Sun) that works pretty well. It isn't as feature full and easy to use as Parallels or VMWare Fusion, but Virtual Box is free. All require a valid Windows install/license.
I would recommend Virtual PC for Mac from Microsoft. They keep images of various windows builds for developer to use. They're basically Windows and the Browser only.