How ading flags for usbasp ?

Arduino IDE support this option ?
i want adding slow and fast boundrate for my USBasp programmer
key -B0.5 and key -B3
Set in
\hardware\arduino\avr\programmers.txt
-b10 key

usbasp.name=USBasp
usbasp.communication=usb
usbasp.protocol=usbasp
usbasp.program.protocol=usbasp
usbasp.program.tool=avrdude
usbasp.program.extra_params=-Pusb  -b10

But zero effect

thank's

answer

\hardware\arduino\avr\programmers.txt
Заменить на: usbasp.program.extra_params=-Pusb -B0.5
set ISP speed 1.5MHz very fast update sketch!

(This key work only with new firmware in usbasp)