I've followed the lead of OLPM and created symlinks for ssl_openssl.pas, ssl_openssl_lib.pas and jedi.inc in the synapse_downloadengine directory.
Currently having problems building for Qt5 and unused packages and links have to be removed using the IDE, but I think it's good enough since it allows me to regenerate my working IDE etc. in a controlled fashion.
The form of --add-package-link in the --help output etc. appears to be wrong: the .lpk shouldn't be supplied as a parameter to the option but as the final parameter that the program is working on.
Updated shell script attached.
MarkMLl