How do you play the guitar part in "Hide the Bone"?

Though famed for my rock playing, I'm not too clued up when it comes to funk, like on "Hide the Bone" (from Crystal Ball Disc 1.) I think its a great track but I'm having trouble working out how to play the main riff/lick, or whatever you want to call it. Does anybody know what chords or phrases Prince uses on this song? (simple written explanations should do, I'm not expecting tab.)

It's a very easy pattern. I don't even know what key it's in, but, play a barre E and then a barre A. Leave the bottom two strings out of it;
You hammer on the third string from a minor to a major, (if you're in A, hammer on from 5th to 6th fret) while you're barring across the 5th fret with your index finger.

THEN, use your ring finger to barre a D at the 5th fret, so, um, index across the 5th fret, ring across the 7th fret.

Then do the first part again.

Thing is, I'm not sure if you do that pattern in the root position, or do you move up 5 frets. I don't have the song in front of me, but that's the basis of the chord progression, E-barre to an A-barre. I'm sure there's some guitar player that's dweebier than me who can tell you the exact chord names, but I call it I-IV and back. (I being the root, IV being the 4th position (E to A).

Now I've gone an over complicated things. Sorry.

Eddie Van Halen wants to know how to play this guitar part!