Ahh, I see 2 questions:
- Can you use Sandboxie to install multiple versions of IE?
- You'd like to know if your idea here would actually work
As to question one: Yes you can. See this and this answer to this question on SO: Cross-browser testing: All major browsers on ONE machine. Release some further googleduckduckgo-fu on the sandboxie forums for further browser-specific details (and ready-made templates etc.).
As to question 2, I wonder: why the hassle (with the VHD hassle)? Simply create different sandboxes for each IE version (and one for your actual use while you are at it)!
The neat thing is that you could run IE6, IE7, IE8 etc. SIMULTANEOUSLY, that is if you have a licensed version of sandboxie (even in august 2014 one can STILL find and buy a legal life-time any-pc-you-own sandboxie license if you live in a useful google-bubble).
However, even with the VHD hassle it would work since sandboxie offers everything one needs to make it into a portable 'virtual' application-layer (you could even carry (and run) your personal installations around on a USB-stick).