Is it possible to make the guitar finish less glossy? Right now it feels like a mirror to me.
Honestly the only way I can think of is some fine grit sandpaper and elbow grease... but it is gonna shine back up when you play it (oils from your skin and movement of said skin will act to polish it back up).

The only true way to make it more satin/ glossy would be to sand it off and reapply a satin/ matte clear coat or just oil it up.
'11 Gibson LP Jr.
'07 Gretsch 5120
'69 Tele
'10 Godin 5th Ave. Kingpin
'03 Blueridge Dreadnought
'02 Custom Martin D-28
Premier Twin-8
Fender Hot Rod Dlx
Boss SD-1
buy a satin finish guitar, unless your a professional, you'll screw up not just the finish but the sound aslo. using a fine(1600 grit) paper will leave swirl marks in whatever pattern you do. live with it or get a different one.