is there any way to make the serial port on the raspberry pi operate at 250kbits

I would like to have the Pi be controlled from DMX commands and need to receive at 250kbits for DMX. I have messed around with setting the baud rate and even changing the baud clock initialization in the config.txt file without much luck. Doesn't look like I can get it much faster than 38kbps

Appreciate any ideas.