ShaderFX, worlds most integrated and artist friendly real-time shader tool, is now available for 3dsMax 2010 (32 and 64 bit).
Why bother with external shader tools that require cumbersome exporting/importing and only offer non-interactive feedback, when there is a fully integrated editor available!
ShaderFX is free for individual use (companies require a license).
Get it at: www.lumonix.net/shaderfx.html