Apply by doing:
        cd /usr/src
        patch -p0 < 002_ifmedia.patch

And then rebuild your kernel.

Index: sys/net/if.c
===================================================================
RCS file: /cvs/src/sys/net/if.c,v
retrieving revision 1.21
diff -u -r1.21 if.c
--- sys/net/if.c	1999/08/08 14:59:02	1.21
+++ sys/net/if.c	1999/11/11 01:22:15
@@ -622,8 +622,11 @@
 
 	case SIOCADDMULTI:
 	case SIOCDELMULTI:
+	case SIOCSIFMEDIA:
 		if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
 			return (error);
+		/* FALLTHROUGH */
+	case SIOCGIFMEDIA:
 		if (ifp->if_ioctl == 0)
 			return (EOPNOTSUPP);
 		return ((*ifp->if_ioctl)(ifp, cmd, data));