You can always cut down on size by discarding a few unnecessary features of the TCP/IP protocol (e.g. move from TCP to a "reliable" version of UDP maybe) You could also try implementing it in asm!! :))

Also you don't need a uC with lots of flash to implement it.... you can dedicate an entire uC to act as the TCP adapter, and use it like you would any UART chip. I think an 8051 + code will be cheaper than one of those COTS ethernet ICs?

Kundi