Regarding the pumpkin seeds: I pulse them in a coffee grinder before adding them to the mix. It does a better job at grinding them down than a blender or food processor. This enables you to avoid over pulsing the mixture just to get the seeds fine.
I'm considering grilling (fire roasting) the seeds, too, but it seems like it would be a pain. I don't have a grilling device to aid with that.
Someone here posted the idea of fire roasting a poblano. I like that idea and will try it. The recipe doesn't call for garlic, but our grocery has Mexican garlic right now (it's purple). Fire roasting the garlic will add more along that theme.
Note, I've never had the original, so I'm really just trying to achieve a really good, unique salsa.