"He uses the little toe to activate the device."
Translation:jan chu'meH ghaH Qay'.
jan chu'meH QaywI' lo' ghaH would be a grammatically correct sentence in Klingon (notice you had the verb and object switched), but might seem a little odd in Klingon. A little like saying, "he used his knee on his opponent's gut," rather than, "he kneed his opponent in the gut." In English there are very few body parts that we can use as a verb - knee, elbow, and shoulder, that's all that come to mind. So for most other body parts we say "he used the body part to..." In Klingon, the finger (and toe) words are used directly as verbs and so it can seem odd to use them as nouns. Thus an English sentence that says, "he uses the particular finger to..." is going to match up with a Klingon translation that uses the finger word as a verb.