Instructions on how to post code:
http://www.8052.com/forum/read.phtml?id=82476

OK, so I've suggested driving all three simultaneously three times now:
http://www.8052.com/forum/read.phtml?id=85114
http://www.8052.com/forum/read.phtml?id=85171
http://www.8052.com/forum/read.phtml?id=85195

Perhaps an example would help:

// Your original Port bit definitions
sbit ibutton_io_1 = 0xA0; // P2.0 – Read 1 
sbit ibutton_io_2 = 0xA2; // P2.2 – Read 2 
sbit ibutton_io_3 = 0xA4; // P2.4 – Read 3 

// Bit-addressable buffer for the 1-Wire lines 
unsigned char bdata ow_buf;

// Inidividual bits in the buffer 
// Note that these bit positions must match the Port bit positions!
sbit  ow_buf_1 = ow_buf^0;
sbit  ow_buf_2 = ow_buf^2;
sbit  ow_buf_3 = ow_buf^4;

//***************************************************************** 
// OW_RESET 
// Function description: 
// Performs a reset on all three one-wire busses and returns the 
// presence pulses detected in the global bit-addressable buffer 'ow_buf'. 
//
// When the function returns, the Presence Pulse values are in 
// the buffer bits:
//   1 indicates no presence pulse on the corresponding line;
//   0 indicates a  presence pulse on the corresponding line.
//
// Reset is 480us, so delay value is (480-24)/16 = 28.5 - we use 29. 
// Presence 70us later, so delay is (70-24)/16 = 2.875 - we use 3. 
//
// Return value: None
// *****************************************************************
void Ow_Reset(void) 
{ 
   ibutton_io_1 = LOW;  // pull 1-Wire line 1 low 
   ibutton_io_2 = LOW;  // pull 1-Wire line 2 low 
   ibutton_io_3 = LOW;  // pull 1-Wire line 3 low 

   uDelay(29);          // leave them all low for 488us 

   ibutton_io_1 = HIGH; // allow line 1 to return high 
   ibutton_io_2 = HIGH; // allow line 2 to return high 
   ibutton_io_3 = HIGH; // allow line 3 to return high 

   uDelay(3);           // wait for presence 72us 

   // Sample each line for a Presence Pulse
   ow_buf_1 = ow_io_1;  // Read 1-Wire line 1
   ow_buf_2 = ow_io_2;  // Read 1-Wire line 2
   ow_buf_3 = ow_io_3;  // Read 1-Wire line 3

   uDelay(?);           // wait for 410us (the remainder of the timeslot)
} 

Notes:

I've assumed Keil, which insists that bit-addressable objects must be global (or, at least, file scope?)

You may need to adjust the timing a little to allow for the extra read & writes.

The Presence Detect states are inverted with respect to your original.

Depending on what else you have on P2, you may be able to just write & read the port in a single byte operation?

You should think about what happens in the event of a fault causing a short-circuit to ground on a 1-Wire bus...