There are a few different paths you can take on it, and more out there Im sure.
One way to go is "Scientific Magic" - This is where you have some kind of Magic Energies, but it otherwise behaves (somewhat) scientifically. Dresden files leans this way, but the best Ive seen is actually the Young Wizards series by Diane Duane, where magic is formula-based using the Speech, and is essentially giving you access to the Source Code of the Universe. You want to go to the moon and you have to write a spell, a set of instructions to the universe, to relocate you and a bubble of air somewhere else, and another to hold that bubble of air when you get there, and a third to keep you from freezing or being blasted by solar radiation. Energy is conserved, but its subsidized by the Powers-That-Be that gave you the magic in the first place, and it still takes more to go to the moon than come back because you have to fight more gravity. More powerful wizard could create objects of pure magic by spelling out (hehe, get it?) that the spell energies need to hang out in a certain shape and pretend to have mass, color, etc.
Another way is to SteamPunk it. The CA idea of Furycraft would fall into this category. Its where you have somewhat recognizable technology, but its explained using a different set of rules, or a slightly warped version, and let things fly from there. This works best when you are trying to highlight the strangely familiar, and usually requires an industrial society. Most often there is a single explainable difference, a deus ex machina material, or some other divergence point for the technology. Ive seen it done where humans are born with a natural telekinesis that only affects quartz crystals. There are basic motors and things, Press Guns that mechanically shove a bolt like a spring-loaded crossbow, and refined "flexible quartz" that made Mech Suits possible. But their development had always focused on crystals, and had the hard limits on how fast and hard a single person could push the crystals. Thus when a Metal mech suit with electronic systems was dug up, it blew everything else away.
The third way is cloak science in Mysticism. This is where you have Mages in robes and towers, waving their hands and chanting, but its all just show to conceal the real secrets, which are all chemistry and physics. It doesnt have to be pure science either, to have teh same appeal. Years ago I read a series that was the Aurtherian tale from merlin's point of view. But Merlin was an demon trapped in a human body by angel, which are all beings that existed in a state of ignorant unity before the big bang, and one day got expelled into cold reality for some reason; angels kept a burning pice of pre-existance, and demons threw their's away when it got too painful. Norse Gods where living beings of electricity that lived in the branches of the "world tree" (ie the layers of the earths electromagnetic field.) It was all about explaining the legend in terms of science and quantum mechanics (which lets face it is a form of mysticism as much as any hoodoo). Even the Sword and the Stone was a magnetic effect...
Those are the main ways Ive seen it done, and there are many others out there Im sure. One big consideration is whether there will be any actual science, or more traditional Magic, to contrast your Technomancy. That tends to make it easier, if more contained.
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