Here's an excerpt from my LED Sign firmware.
I used 115200 on an AT89C51ED2.
I bet you can figure out the correct new value for 57600.
Good luck!

;-------------------------------------------------------------------------------;
;			L E D   S I G N   F I R M W A R E			;
;-------------------------------------------------------------------------------;
;Source file:	LED SIGN.ASM
;Version:	1.0
;Date:		Feb. 2006
;Application:	AT89C51ED2 in X2 Mode @ 11.0592MHz, All peripherals in X2 mode
;IDE:		Keil uVision v2.4
;Toolchain:	FLIP v2.4.4
;Author:	payam7777777@hotmail.com
;Major Changes: . 
;-------------------------------------------------------------------------------;
;			I N T E R R U P T   M A P				;
;-------------------------------------------------------------------------------;
;TASK	|SOURCE	|PRIORTY|FREQ.	|LENGTH	|CPU	|STACK	|ALTERS			;
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;RECEIVE|SERIAL	|3      |11520Hz|18.44us|21.25 %|2 BYTES|NOTHING BUT GLOBALS	;
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;-------------------------------------------------------------------------------;
;			I N T E R R U P T   V E C T O R S			;
;-------------------------------------------------------------------------------;
.
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	ORG	0023H		;Serial interrupt
	JMP	SERISR		;Serial ISR
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;-------------------------------------------------------------------------------;
;			S E R I A L   I S R					;
;-------------------------------------------------------------------------------;
SERISR:	PUSH	PSW		;24
	PUSH	ACC		;24
	CLR	RI		;12
	MOV	A,SBUF		;12
,
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,	POP	ACC		;24
	POP	PSW		;24
	RETI			;24
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,
;-------------------------------------------------------------------------------;
;				M A I N						;
;-------------------------------------------------------------------------------;
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	CALL	INITSRL		;Initialize Serial@ 115200 (Mode 1, IBDRG)
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;-------------------------------------------------------------------------------;
;			I N I T S R L   S U B R O U T I N E			;
;-------------------------------------------------------------------------------;
INITSRL:MOV	SCON,#50H	;Mode 1, REN=1, SM2=0 => RB8(SCON)<-stop bit
	ANL	BDRCON,#0EEH	;BRR=0, SRC=0
	ORL	BDRCON,#0EH	;TBCK=1, RBCK=1 => IBG for T&R, SPD=1 (FAST)
	MOV	BRL,#0FDH	;115200 with 11.0592 in X2
	SETB	ES		;Enable serial interrupt
	SETB	EA		;Enable global interrupt
	ORL	BDRCON,#10H	;Baud rate generator run
	RET
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;-------------------------------------------------------------------------------;
;					E N D					;
;-------------------------------------------------------------------------------;
	END