Of course you can change your accent. It takes a long time to break subconscious habits but people do it all the time.

I'd like to point out that accent and pronunciation are functions of each other. If your accent changes, your pronunciation would also. Likewise if your pronunciation changes, your accent will also. Even if it's only temporary, like during/for a play or a poem, they change with each other; you can't change one and not the other.

At any rate tdol's totally right.. the mark of fluency in another language usually involves being able to fool a native speaker into thinking you're one too :)

-Nah-