Technically, you're meant to use human servants/slaves. If absolutely necessary, you could get away with transmuting humans into some imp equivalent (which is what I have observed Cav has done for The Flesh, which is understandable because there is little or no believable way to get humans to work for that abomination without dying). If you have no means of obtaining human help now, what you could do is build your Heart yourself (at minimum you can find some shack/cave and enchant some rock and call that your Heart, although you might do something fancier with Runes), then create minions to go enslave human workers.

If you are near the Ashmarch or Kythnos, then enslaving some of their inhabitants or tricking them to do your dirty work would be easier than the Cypriots. Hey, you could even break out a bunch of prisoners/slaves from those people and put them to work as your own.

Of course, you could always go the more traditional route of simply enslaving villages and, until you get your own industry going, pillaging all supplies from villages, but that would have the drawback of drawing a lot of unwanted attention rather quickly. You may be able to get away with snatching a few individual farmers, provided you somehow shield their minds from Reginaldus' detection. Considering that Emily and co are aware there is someone who pries on them in their sleep, they may consider it a good idea to shield their Dungeon from such intrusions (using Runes, probably), which would incidentally serve the purpose of hiding workers too provided they don't escape.

These are just suggestions, of course. Ultimately it's up to you how you want to tackle it.