Use ssh(1) to connect to your home machine, use su(1) or security/sudo to become root. Then use the same pkg-install(8) commands.
A good Windows SSH client is PuTTY.
You will have to enable port forwarding on your router at home. Normally no incoming connections are forwarded. In the case of SSH you will need to forward port 22. You'd then connect to your home internet address from your workplace.
A good Windows SSH client is PuTTY.