If you don't include "modedefs.bas" the second "0" will refer to T2400 bauds.

Since you're using the demo, i'm not sure if they include this "modedefs.bas" file. BTW i never place this include, i use specific VAR or i let it like that and i place comment at the right edge of the line.

Code:
TRISB.0=0 ' set PORTB.0 as output
SerPin var PORTB.0 'alias to PORTB.0
T2400 con 0 ' Alias to 2400 baudrate mode true 
            ' for SEROUT

start:
      serout serpin,t2400,["hello"] ' send hello @2400 bauds
      pause 1000 ' wait 1 second
      goto start