Iuri, the client-side ns_httpsget command is part of nsopenssl.
Naviserver does not use seem to use nsopenssl at all, instead it has
the nsssl module.
Unlike nsopenssl, the nsssl module does not include any extra Tcl
code, but it does appear to implement client-side support (in C)
in its ns_ssl Tcl command. And it looks as if OpenACS does use ns_ssl
in its util::http::* commands, so Gustaf is of course correct that you
should try that stuff first. (Did it work for you?)
Btw, if you need client-side cookie support, way back in 2003
tclwebtest had it.
It was fairly easy to copy the relevant small amount of Tcl code and
modify it to work in AOLserver and OpenACS. With that sort of cookie
support, I was able to e.g. make AOLserver log into an OpenACS site.
Maybe there are better solutions by now.