You could put it somewhere between a potion and a focus/enchanted item.  Leave the slot open, and apply your Deal Du Jur at the start of play.

Only with sponsor debt.

Conjuring
Binder's critters looked human.  Any conjured ecto-shell could look human with some spirit stuffed into it to animate the thing.  The spirits in question could vary wildly in power.  It's all a matter of getting some spirits willing to work with you (Lets Make A Deal) that are capable of whatever you want the shell to do.

Someone with more talent than Binder could probably vary the shells so they're not all identical.


Scions
The half mortal children of some beast or other could easily look normal while still packing various Inhuman powers.  An entire plot line might revolve around hunting down the parent of this Gaggle Of Doom and putting and end to them.

Shape Shifters
Any number of critters out there might be capable of changing shape to look human.  Make Stuff Up.

The Nagliosshi apparently taught a group of mortals some of their tricks, "Skin Walkers".  Expect these people not to play well with others.

Puppeteer
Mortal body with Something Else calling the shots.

Possession: A demon, ghost, or other spirit takes over.  IIRC, there's a write up for this in OW37.  No stat block, just some guidelines.  The Denarian's qualify. 

Physical take-over: Something physically crawls into a person (star trek 2-style) and runs the show.  Adrenal control and "I don't much care about the body I'm controlling" could add up to some inhuman powers.  Star Gate's Gu'auld are another example of a hyped up body as a direct result of a physical take over.

Remote control:  This probably wouldn't work for a group of thugs, but someone could go all voodoo and literally pull a vanilla mortal's strings.

Amped up mortals
We've already seen the hexenwolf belts in Fool Moon.  Some other Enchanted Gizmo could produce other powers in normal people (almost certainly at some cost).  A retrofitted Lycanthrope would probably have many of the same psychological issues as the hexenwolves.  This retrofit needn't have the "5 days of the month" limitation that the real deal has either.

Hey!

Lycantrhopes
"Shapeshift" the mind instead of the body.  We've already seen a gang of them in Fool Moon, the "Street Wolves".  Perhaps they'll hire themselves out as heavies.  And they can't be the only such group in the world.  They're limited to the 5 days around the full moon, but that can't be too hard to work into your campaign.

And the mind they shift into need not be wolves, or even predators.  Ursanthropes, and, Bovinethropes, and Equinethropes!  Oh my!


Used To Be Something Else
A sufficiently powerful thamaturgist can shape-shift a being against their will.  I suspect this is much easier when the recipient is willing.  So grab a bunch of goblins or what have you, and transform them to look human.  Again, they'd need Deals.


Illusion of mortality
Easier still if its a glamour instead of an actual transformation.  A ritual-based illusion could last quite some time with enough juice.  If the critter in question is supplying the juice, it takes no effort at all on the part of the summoner.

Not entirely correct - while different from a normal compel it is still called a compel.  The specific text states "This is a chain reaction - the first player calls for the compel, and if the GM accepts it as valid, she negotiates it with the player of the target character, who either decides to accept (gaining a fate point) or avoid (spending a fate point)."

It is different from a standard compel in one case - the initiating player doesn't get his fate point back (nor receive an extra) if the target player buys out of it.  Source is YS107. 

<Insert my standard rant on needlessly obscure terminology used by DFRPG here.>

Also:

Once the initiating player spends the fate point,
he does not get it back even if the target buys out of
the compel.

Emphasis in the original text.

You could do it with a goal of passing fate points around.  Everybody give the wizard grief, but when the time comes, he can manage some Major Mojo.

"He Does Good Work" Use craftsmanship instead of presence for  "Reputation" within the local supernatural community (his customers and their friends).

Figured mine out a couple weeks ago.  Check the sig.

I think you're drawing an unnecessary parallel between the way an enchanted item works (like Harry's rings), and a thamaturgical spell.

The Enchanted Item is powered by keeping back just a little bit of motion every time Harry so much as twitches.  This energy is stored, and then released all at once.

Thameturgy takes a while to cast, and the effect draws all the power from the act of casting itself.

So in this case, there's no need to generate a pile of bad luck to match your good luck.  All the generating happens during the casting of the spell... the spell energy is converted to Good Luck (or whatever).

Again, there's no fountain-of-good-luck parallel in the books due to bad luck curses, so I don't even see a "canon" reason to require it.

The rules don't require it.  The setting doesn't require it.  Don't require it.