Wiggle the toothpick around until the hole is big enough (but not huge). Use toothpick to carefully ease the root into the hole.
Once you've got it in, press the soil far from the outside to close the hole, perhaps from the rim of the pot with a flat spoon handle or similar. The proceed with the mister to compact the soil, as Zath describes.
The roots of rosetted sundews are actually not that sensitive---they're not like pygmies etc. I never lost a rosetted sundew repotting it this way. Still be careful. The less damage you cause, the less time it will take for the plant to recover. If you can leave a plug of medium around the roots, do!