Digging around a little has yielded pretty good news regarding Ranger preseason broadcasts; of the six games on the schedule I've found commitments to 4 being shown on TV and I'd hazard a guess that at least one of the remaining two should be available.
9/20 TUE at NYI 7:00 PM FSNY per Isles official Web site
9/25 SUN BOS 5:00 PM MSG per MSG Network schedule
9/27 TUE at NJ 7:30 PM ??? nothing on Devils site
9/29 THU NYI 7:00 PM MSG per MSG Network schedule
10/1 SAT at BOS 7:00 PM NESN per NESN broadcast schedule
10/2 SUN NJ 5:00 PM ???
9/27: does anyone know where an Fox Sports NY broadcast schedule can be found?
10/1: obviously this is only of value in the NY metro area to satellite subscribers
10/2: I'm optimistic that a home game vs Devils late on a Sunday afternoon ought to be broadcast, but who knows? October dates are not yet available on the broadcast schedule websites that I checked.