It starts out simple, just hammer on the second and pinky fingers, pull off to the first finger and repeat, like Ex. 1. Do it over and over and it sounds fast, but kinda boring. Now we'll move it around a bit.
Examples 2 and 3 play through a three note per string C Major scale using the same finger motion. Example 2 is straight through the whole scale, Example 3 is in groups of 9, or up three strings, down one.
Example 4 is where we start getting into some less conventional left hand stuff.
It's the old 1,2,3,4,1,2,3,4 sounding thing with a twist. Hammer the first two notes on the 6th string, pick the fourth note on the 5th string and hammer the middle finger back on to the 6th for the next note. We are crossing strings with the hammer ons now, it takes some getting used to but do it enough and it will be as easy as example 1.
Example 5 elaborates on the crossing strings with hammer ons creating a more angular type of sound, this time hammering with the pinky. We are still using the same finger pattern as Example 1 for all these exercises!
Example 6 is a descending pattern in the style of Shawn Lane. This one is not easy at first. It took me about a year to be able to do it smoothly.
The example is a combination on scale and arpeggios that sounds a lot harder than is actually is.
Try to apply these patterns to other modes, three note per string pentatonics or wherever else you can imagine it happening.