I would be glad to help you with this technique...On the old MS there was a thread like this, but it wasnt about "learning" the technique, I think it was called "how did you learn to play sweeps" or something like that...Anyways...If you dont know what sweep picking is...Well...When you're playing fast licks where the notes lie on different strings (like an arpeggio) its hard to get the desired speed using alternate picking...so you need Sweep Picking...to do this, your pick should flow across the strings using one smooth picking motion, you need to let the pick fall from string to string, so its like strumming a chord...your right hand should be like strumming a chord, but at the same time your left hand should be playing the individual notes...you can play each note individually by lifting your finger away from the fret enough to mute it...cause each one should be muted right after you have hit it ...or else they would ring together and sound like a chord...I dont know, its very hard to explain...it can take some...you'll think its easy at the end...so be pacient and take your time...

Sweep Picking should sound like this (just in case you dont know)

http://youtube.com/watch?v=ovPXquI3GBk

If you need some extra help, you can check this site

http://youtube.com/watch?v=3mbx03mP5eg
this guy is awesome, and he really helped me out!!!

Some basic exercises...

||--------12-17-----------10-15---|--------8-13-----------10-15----||
||-----13--------------12----------|-----10-------------12------------||
||--14--------------12-------------|--10-------------12---------------||
||-----------------------------------|-----------------------------------||
||-----------------------------------|-----------------------------------||
||-----------------------------------|-----------------------------------||

||--------12-17-12---------------||
||-----13----------13-------------||
||--14----------------14----------||
||----------------------------------||
||----------------------------------||
||----------------------------------||

1 4 3 3 2 1 4 1 2 3 3 4 1
||----------------------12h-17p-12----------------------||
||------------------13--------------13--------------------||
||--------------14----------------------14----------------||
||----------14------------------------------14------------||
||--12--15--------------------------------------15--12--||
||---------------------------------------------------------||

the finger positions are almost the same here

||--------------5h8p5---------------------||
||------------5-------5--------------------||
||----------5-----------5------------------||
||--------7---------------7----------------||
||------7-------------------7--------------||
||--5h8-----------------------8p5--------||

If you're a really good player
you may think these are too easy...
so I'll post harder licks later...

Good Luck!!!