As with every thaumaturgy magic (or every action in general), the more important question to "how" would be "why".
If you just create a construct to stand there in the corner, that's not going to be very interesting. Have 100 of them, for all I care.
Now when it comes to using them, that's when it gets interesting.
So I'd probably come at this from a totally different angle. So when it comes to a necromancer or an artificer, I'll assume that they'll have their undead or golems in arms reach, unless explicitly told otherwise. After that, it's basically the way they channel their magic.
So when Grevane attacks Harry, he does a regular necromancy magic attack spell, but instead of hurling dark energy at Harry, he sends his reanimated goons. Those goons are always with him, that's just his style, that's what allows him to do his magic. If he were a player character and needed to go somewhere he couldn't bring his chaps, he'd get a fate point for the trouble.
Likewise an artificer with a golem. If he wanted his golem to burst through a wall, he'd roll on a maneuver spell against the wall's strength, and if he succeeds, the golem bursts through.
Now one thing that creatures like allow for very nicely is sponsored magic and especially evothaum. You don't need to do a long ritual to break down that wall, you can do it immediately. You need some extra juice? Overload your golem. It might break down later, but at least you're through the wall.
Of course, the best way to play a big creature like that would be for another player to pick up the sheet and play it as their character.