Thanks for your reply. I did something like this and seems to work.

#include <reg51.h>
//cout	EQU		0x0030	;Send Acc to serial port
extern void cout(unsigned char dato)
{
	ACC = dato;
	#pragma asm
		lcall	0030h 
	#pragma endasm
}

//cin	EQU		0x0032	;Get Acc from serial port
extern unsigned char cin(void)
{
	#pragma asm
		lcall 	0032h
	#pragma endasm
	return ACC;	
}

I don't know if there is a "more elegant" way of doing this. Is this what you mean with "skeleton"?

thanks,
Jorge.