The mast DSP clock limit is one, at which Your N900 DSP will fry out of blue sky. Go To Find Out i(t) Yourself.

And, vi_ is right recommending You to wait for it being integrated into CSSU or whatsnot. If You can't achieve it following already published tutorial, don't touch it. Unless You got really specific and sane question, that show Your ability to at least understand the process.