Installing ports is simple.
When you clone the stanix repo you get a ports folder, once stanix is built just go into it and use build and install to install all ports you want.

./build.sh XXX
./install.sh XXX

where XXX is the name of the port. Rebuild the initrd and the disk image (using make iso or make hdd) and you’re done !

See here for a list of all the availables packages and ports.