audacious : mousewheel volume control

[orang Aumori Jepun <mahu_berehat@yahoo.co.jp>]

Hi, all.

I'm using Debian Squeeze.
While I'm using audacious music player, I can increase/decrease audio volume by 5% with mouse wheel.
But , I want change the 5% to 1% or any value I want.
Anyone please tell me how to do .
Ubuntu hardy had a preference menu to change the value , but debian squeeze does'nt.

I downloaded the source of audacious-plugins , and I found in PO file , there is a description "mouse wheel value ......", but I could not go further .

TIA.