Using Tor as transparent proxy ?

[Aguywhoneedshelp]

Hey there,  I need some help.
I want to setup a transparent Tor gateway and because I already know pfSense I would like to do it with pfSense and not OpenWRT or something.
I tried following this guide for FreeBSD (http://0xfeedface.org/2013/06/25/tor-transparent-proxy-on-freebsd.html), but like it says in the guide, there is an error to be expected because Tor tries to access /dev/pf without the right permissions.
Solution in that guide is to put 'own pf _tor:_tor' >> /etc/devfs.conf which I did, but every time I try to start Tor it says
"[warn] open("/dev/pf") failed: Permission denied"
The weird part is, if I restart the devfs service the error dosen't show up, but Tor seems to freeze at that point and is not running.
If I reboot the system it's back to the old "Permission denied" error.

Could somebody tell me how I can resolve this issue ?
Thanks