No, that won't work. Nothing you do client-side will help.

OnLive Client <-all input is transmitted-> OnLive Servers <-filter out Enter-> Deus Ex instance in a VM.

The enter key is filtered out on their servers. Unless you hack into their servers and change that, there is nothing you can do on the client-side. That's what makes you completely helpless.

Ah, my apologies, I thought the game was running locally. (This sort of assholeness on the part of servers is basically why 'cloud computing' is such a bad idea.)

I disagree that cloud computing is a bad idea because of this. It has advantages and disadvantages. Not being able to hack around to make changes you wish is a disadvantage, but having access to something you would not have otherwise is a much bigger advantage.