Forum OpenACS CMS: forward port 80 to port 443 and upgrade to secure connection
Actually one should get this more or less out of the box, when installing OpenACS via . After installing, install a certicfiate and activate https (i.e. uncomment "set httpsport ..." in the config file). The default config file openacs-config.tcl  is installed by  by default as /usr/local/ns/config-openacs-VERSIONNUMBER.tcl (e.g. openacs-5-9-1.tcl).
all the best