I guess you came here becuase there is no activity in the Massuchusets Forum.
I do not have any specific frequencies nor will list ones I may be able to find on the internet since I can not say how accurate they are, but a good bet woudl be to check between 450-451Mhz and 455-456Mhz during commute times. You should pick them up there. Those frequency blocks are usually used by TV/Radio including news helicopters.