I presume if you are in a different subnet you would want PrinterB or PrinterC
Code:

Select
	Case instr(@IPADDRESS, "192.168.24.")
		$ = AddPrinterConnection("\\Server\PrinterA")
	Case instr(@IPADDRESS, "192.168.25.")
		$ = AddPrinterConnection("\\Server\PrinterB")
	Case instr(@IPADDRESS, "192.168.26.")
		$ = AddPrinterConnection("\\Server\PrinterC")
	Case 1
		; Something Else
EndIf

And what if you have a fixed and a wireless NIC in your portable...