If you haven't read up on scale and chord theory, check out Tom's Visualizing the Fretboard tutorial, and Jody's lesson on Nashville Numbers. This sequence will work over the basic corresponding chords of C Major, but would be better fit if you add the a 7th into the mix.
Cmaj7, Dm7, Em7, Fmaj7, G7, Bdim7, Cmaj7
Personally, I find this type of run easiest to play if I really exaggerate the hammer-ons and pull-offs. If you focus on slamming your finger against the fret, you'll get best results.
Practice hard, and see you next time!