Try a software UART, code is at silabs, for your second UART. That way you can use the same stuff you already have. It will take away some of the processor steam but you can use timer interrupts to keep the overhead reasonable.
Sorry, I acidently started a new thread.
However the code will work with slight modification on other generic 8051 derivatives, that do not have a second UART. Also the process is heavily documented here and you can get more such code at Atmel and other places.