I believe using the null governor should work; however, mine currently seems to be latched at 400 regardless of what governor I use (even powersave!) so I can't test.

My experience, way back when this was first making the rounds after OS2008 was released, was that the performance kick was not significant, but I was thinking to try it now... maybe that's why?! (No, I know ondemand did work at one point. So I'm not sure what's up with this right now... I blame liqbase, though.)

EDIT: Well, going into liqbase, setting ondemand, and exiting leaves me with ondemand behavior, and then I can switch it via /sys/.../cpufreq/scaling_governor as expected.

Turns out null locks it at current speed, so you need to kick it into performance, then to null (naturally, you don't want any BT tasks running at the time, or you'll lock in 330); also turns out that BT encoding for HSP is not done as a DSP task, because it doesn't pull us down to 330, but playing mp3s in Media Player does.