You can grab an already made archive:
cd /tmp ftp http://ftp.openbsd.org/pub/OpenBSD/$(uname -r)/ports.tar.gz ftp http://ftp.openbsd.org/pub/OpenBSD/$(uname -r)/SHA256.sig signify -Cp /etc/signify/openbsd-$(uname -r | cut -c 1,3)-base.pub -x SHA256.sig ports.tar.gz su cd /usr tar xvzf /tmp/ports.tar.gz
And voila
You can also get the ports through cvs.
The first time using:
cd /usr cvs -qd anoncvs@anoncvs3.usa.openbsd.org:/cvs get -P ports
Grab a coffee
Then upgrade it with:
cd /usr/ports cvs -q up -Pd