Information or reference?

Could anyone supply information or a reference that would help getting the sybase_ct extension to PHP4 building as a shared module rather than a static one? I can make whatever modifications I need to to the code etc, I have tried for a few hours by using the mysql ext as an example but I don't seem to be able to achieve whatever it is that gets it to build as shared. I have specified "shared" on the ./configure line, and I'm using freetds which has a shared lib variant so in theory it should work, probably just missing some changes I need to make somewhere? Richard.