How to set 250000 baud rate in pyserial ?

[kurabas]

I use Arduino 1280 and Arduino 2560 under Fedora 15. 
1280 creates ttyUSB0 port  and can be set at 2500000 successfully.
2560 creates ttyACM0 port and can be only set at speeds from list (no 250000) 
in pyserial. How to set 250000 to ttyACM0 port?? Need I patch kernel or python?
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