An EPK of lwip is available from http://humans.iv.ro/jani which has the most
up-to-date package (at least until it all gets integrated).

It has just been tested on another ARM similar to the EB40 with CS89000
and it works there too (that board has 128K of RAM).

Alternatively, lw.diff is the diff against the lwip-0.5.3 tree. It contains
eCos support + an eCos project sample based on unixsim. Look at
lwip-0.5.3/proj/ecos to see how to use it. Modify the Makefile to suit
your needs and to reflect your eCos project dir.