They should be able to setup both your modem, router and splitter for you, yes. However, what you need to becareful of is that some providers will charge a small fee for doing this, and you can save money by doing it yourself. That being said, some splitters are screwed into your wall and you have to attach wires into a box which, isn't something most general consumers can do. Other splitters are easier and you simply plug them into two phone lines and you're good to go.
