Non-standard baud rates with Serial Monitor on Arduino IDE

Is there a way to set serial speeds in the Arduino serial monitor other than the standard serial speeds that top out at 115,200 baud? I would like to try communications at 250,000 baud, a speed allegedly supported by the Atmel microprocessor...

I poked around the preferences.txt file but it and none of the other files I looked into seem to contain the 'legal' speeds that the IDE offers in the serial monitor window (Arduino 022).

the bauds are set in binary I think?

2400
4800
9600
19200
28800
38400
57600
76800
115200
153600
230400