Writing to EEPROM is much more complicated, as you need to check that the EEPROM isn't busy. If it's any help, here are the C functions I wrote.

/***************************************************************************
* NAME: api_wr_eeprom_byte
*----------------------------------------------------------------------------
* PARAMS:
* Uchar xdata * const address : address to read
* Uchar value : data to write
* return:
*----------------------------------------------------------------------------
* PURPOSE:
* This function allows to program a byte in Eeprom. Don't use raw, see
* changeEepromByte()
*----------------------------------------------------------------------------
* REQUIREMENTS: The EEPROM mustn't be busy to perform the write access.
*               Check using __api_eeprom_busy() API
*
*****************************************************************************/

void __api_wr_eeprom_byte (xdata Uchar * const address, const Uchar value)
{
    bit ea_save;

    while(__api_eeprom_busy ()) giveTheDogABone();
    ea_save = EA;
    EA = 0;
    EECON = 0x02;
    *address = value;/* addr is a pointer to external data mem */
    EECON = 0x50;
    EECON = 0xA0;
    EA = ea_save;
}
/***************************************************************************
* NAME: api_eeprom_busy
*----------------------------------------------------------------------------
* PARAMS:
* return: 0 (false) for not busy, 1 (true) for busy
*----------------------------------------------------------------------------
* PURPOSE:
* This function allows to check if eeprom is busy or not.
*****************************************************************************/

Bool __api_eeprom_busy (void)
{
    return(EECON & 0x01);
}
/***************************************************************************
* NAME: api_rd_eeprom
*----------------------------------------------------------------------------
* PARAMS:
* Uchar xdata *address : address to read
* return:
*----------------------------------------------------------------------------
* PURPOSE:
* This function allows to read a byte in Eeprom.
*----------------------------------------------------------------------------
* REQUIREMENTS: The EEPROM mustn't be busy to perform the read access.
*               Check using __api_eeprom_busy() API
*****************************************************************************/

Uchar __api_rd_eeprom_byte(const xdata Uchar *address)
{
    Uchar val;
    bit ea_save;

    while(__api_eeprom_busy ()) giveTheDogABone();
    ea_save = EA;
    EA = 0;
    EECON = 0x02;
    val   = *address;
    EECON = 0x00;
    EA = ea_save;
    return (val);
}

 

The giveTheDogABone() function services the watchdog, so you wont need it if you're not using the watchdog.