Is there a straightforward way to have Lispworks make the connection for Postmodern instead of CL+SSL?
Of course -- the use that's made of CL+SSL is very minimal. If Lispworks also has a 'convert raw socket to ssl socket' function it'll serve just as well as CL+SSL. As I mentioned, the relevant code is in cl-postgres/protocol.lisp. If you can get a Lispworks-specific approach working in a way that is compatible with the CL+SSL code (#+/#-, etc), I'd be happy to integrate it into the distribution.
Best, Marijn