I've tried googling, but a lot of the services I'm finding just don't work. Alternatively, services like Browser Shots are great, but not super realistic for me. I need to have it locally so I can quickly troubleshoot problems. Your tools?
The short answer is, you can't.
You can only have 1 version of IE installed on a single machine so if you have > win XP you effectively cannot have stand-alone IE6.
The only way to get stand-alone IE6 is to use a virtual machine with a copy of Win XP installed. So that means a licensed copy of Windows XP, after having purchased Vista/Win 7.
Or you could use IEtester, which works on Win 7 and is ok. Or use IECollection, which doesn;t work on Win 7 but is amazing on Vista. However, these emulators are not 100% identical to stand-alone IE6