My beliefs are pretty widespread, I like to think that I take the best, and leave the rest.
But as far as magickal disciplines go I'd say Chaos Magick ( in the vein of Austin Spare, Peter Carroll, Phil Hine, William Burroughs, and my personal favorite, Robert Anton Wilson)
would be the most in line with the steampunk ethos. It's sort of a multidisciplinary approach that mixes in modern chaos theory/metaphysics/science with the more (forgive the term) "superstitious" magick of the previous centuries.
I apologize for using the S-word I don't mean to demean or anything, that's just how some magick practices seem to me, but that might be because I just don't understand.
Like at first I didn't understand the LBRP (Lesser Banishing Ritual of the Pentagram) and I thought that it was silly to invoke archangels. However once I found out WHY a banishing ritual is important I realized that they exist in one form or another in all magick practices and I created my own, because for me using the template of a guy who's been dead for years felt a lot like institutionalized religion as opposed to a mystical and personal experience.
I guess what Chaos Magick and Steampunk have in common is a DIY method that isn't "one size fits all"
Now, if you're talking about steampunk as an aesthetic, then I'd say that the Thelemic path is more genre appropriate.
Personally I find Crowley's approach too..... rigid? Too many rules, and there's too much that seems to me to be arbitrary.
It's like rote memorization rather than understanding the principles of how magick is supposed to work.
I like the term Obadiah used "Eclectic Agnostic Occultist" that's me in a nut-shell.
Though I don't really see Pagan as a vague term, as it's sort of an umbrella term that encompasses all poly-theistic religions, but especially the "old" ones that had a connection to the natural world. Though by this definition most Shamanistic proto-religions also fall under the Pagan umbrella.
Jeez, I could go on splitting hairs all day! Kind of a long post considering it's only my second.
But like with all human classifications, you can't draw hard lines and there are always going to be people who feel that they do or don't fit into those labels.