I was going to suggest manually prefixing your 32bit favorites with "c:/Program Files (x86)/Internet Explorer/iexplore.exe"
Example being google.com...
Code:
"c:/Program Files (x86)/Internet Explorer/iexplore.exe" "http://www.google.com"
but I just tested that, and IE reprefixes it with http:// so it becomes
Code:
http://"c:/Program Files (x86)/Internet Explorer/iexplore.exe" "http://www.google.com"
Which obviously wont work.
It will work if you make them desktop/taskbar shortcuts, but not favorites inside IE8.
Edit: Ok, I just tried something else. Create those shortcuts on desktop. Rename it to Google32, then move them to 'C:\Users\username\Favorites
This will now appear in your favorites folder in IE8 as Google32.
Edit2:Clicking on it, will open 32bit IE8 and go to google. But because it is calling IE, it will open in a new window regardless of it you click it from 32 or 62bit IE.
If you want to, make another and remove the " (x86)" forcing it to open IE8 64bit, and go to the URL.