Technically possible and quite powerful.
Machine sprites are very powerful and I like them that way. However, I also like to take advantage of their drawbacks. If they plan on running silent (their icon would be visible to everyone otherwise, and quite odd/suspicious), they get a -2 penalty to dice rolls. If they are seen by someone who would be suspicious (matrix security personnel), they will be aware that a technomancer is afoot. Even if they don't recognize it, sprites can't be part of a PAN, so if it is running diagnostics on something, it will look like a weird extra icon on a device. Might want to prep for that.
Does your team have a technomancer and a decker? Is the technomancer really just there to provide machine sprite buffs? It's nice for a team to have and often worth the split pay, but it is often kind of dull for the technomancer. Are they ok with that? Do they have another role (face, rigger, etc.) It becomes kind of like a tag-along NPC role -- basically making sure everyone has their sprites going and being protected by everyone else, until you get a chance to puppeteer something at an important time or something.
It's not far-fetched to make a technomancer that uses their own machine-sprite assisted deck. Basically, you take a hit to some attributes to trade for dicepool and limit boosts from a machine sprite.
No ally spirits for technomancers.
