Is it possible to undervolt an ati-gpu?

[the.ant]

I have an ati mobility radeon (x1400) in my lapton (t60). The fglrx-drivers have this neat ati-speedstep tool which let's you undervolt the gpu, saving a good deal of power. The downside is of course, that the rest of the drivers are pretty rubbish. Currently I'm using the radeonHD and am quite happy with them, except that I didn't find anything to reduce power-consumption. Is it possible at all?
Are the normal radeon drivers an alternative? Is there any other way?
Has anyone made progress on this one?