I've read of people doing it both ways (shaving, and water/milk titration).
'Seems to me that if it works to mix it in liquid (which dissolves it into the smallest possible state), it would work just fine to 'shave it' (which wouldn't be a thorough as dissolving it as would the liquid).
I think 'accurate weight' is the most important factor (since you're not dealing with a known "time released" type of med/capsule).