my g/f has a ghetto kodak. its a DXG model 518. all i did was set it to the fireworks setting and right before each huge blast of lightning the heat lightning would be real bright, when i saw it get super bright i would click the button. it would take a few seconds to focus and actually take the picture, but those are what i came up with.
i was suprised it worked so well, and after the first one came out decent, i stood in the back yard with my arms straight up for like 30 mins takin shots...

i bet i looked goofy.
that and i got lucky that night, the lightning seemed to hang out for a few seconds as it spidered out. it was really cool.