I guess if you really wanted to do this you could get it all ready prio to the trade taking place.
Get ready by registering a hotmail account filling out all the info needed apart from the actual email address.
When he gives you the email address he wants it changed to, just make it with the same starting letter and go ahead and change it. This way it will look like it's changed and you still have control of the email account.
This would actually work when making the guy trust you as well.
"Account email changed?"
"Ye, you can check it yourself."
I guess when you get the rest of the info you can recall the password into your new email adress. But this all depends on what scam/how you scam.