The easiest way I know to check would be with an LED & a few pause statements. If HSPLL isn't running it will be obvious on the LED.

Main:
HIGH LED
PAUSE 500
LOW LED
PASE 500
GOTO Main

OSC2 can output the clock/4, but only in EC mode. In other modes, the signal from OSC2 output is so weak you'll load it with a scope probe.