Uhh nope. Need the tool. Trust me, been there, done that - I happened to be looking for the Aux in to connect a phone/Ipod to. The silver trim on the left and right of the unit pop off to expose access for the tool to release the unit from the sleeve. Four Winns included the tool in my owners packet for the boat, along with an actual useful Owners manual - included wiring diagrams for the boat systems and aux systems such as the Clarion head unit, Sirius XM aux unit, etc.
My new Chap has the JVC MS3A - round head unit - which you're referring to. Have yet to find a few features on it and bluetooth on it is a PIA. I'm going to end up just using a headphone cable to aux my phone and play Pandora that way. Won't work in the Four Winns opening unless you do a custom filler panel or reglass/regel the opening and then drill for a new round unit.