I was just looking at buying E+ access myself today, so I was surprised to see this thread is only 2 days old.
I'm US Chairmans, so I have the same problem. The summary I took away from this thread is "yes, you can do it, but it's a giant pain and be prepared to devote at least an hour of your life to phone calls every time you want to fly on United". Is that basically correct?
It's ridiculous - if I'm going to spend the cash for E+ access with UA, why should I have to go through this? It's not going to get me to change my FF status to United (they don't operate from my home airport). As far as I can tell, this policy is actually bad for UA, since it means they lose out on my E+ membership fee.