DEFINE for HSEROUT are explained in the PBP manual
The serial parameters and baud rate are specified using DEFINEs:

' Set receive register to receiver enabled
DEFINE HSER_RCSTA 90h

' Set transmit register to transmitter enabled
DEFINE HSER_TXSTA 20h

' Set baud rate
DEFINE HSER_BAUD 2400

' Set SPBRG directly (normally set by HSER_BAUD)
DEFINE HSER_SPBRG 25

HSEROUT assumes a 4MHz oscillator when calculating the baud rate. To maintain the proper baud rate timing with other oscillator values, be sure to DEFINE the OSC setting to the new oscillator value.
In your case, the DEFINE list would look something like
Code:
DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER_SPBRG 25  ' 115200 Baud @ 48MHz, 0.16%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically
HTH