Apply by doing:
cd /usr/src
patch -p0 < 004_i386machdep.patch
And then rebuild your kernel.
Index: sys/arch/i386/i386/sys_machdep.c
===================================================================
RCS file: /cvs/src/sys/arch/i386/i386/sys_machdep.c,v
retrieving revision 1.23
retrieving revision 1.23.6.1
diff -u -p -r1.23 -r1.23.6.1
--- sys/arch/i386/i386/sys_machdep.c 1 Feb 2004 12:26:45 -0000 1.23
+++ sys/arch/i386/i386/sys_machdep.c 13 Jan 2006 04:12:15 -0000 1.23.6.1
@@ -394,6 +394,13 @@ i386_set_ioperm(p, args, retval)
if ((error = suser(p, 0)) != 0)
return error;
+#ifdef APERTURE
+ if (!allowaperture && securelevel > 0)
+ return EPERM;
+#else
+ if (securelevel > 0)
+ return EPERM;
+#endif
if ((error = copyin(args, &ua, sizeof(ua))) != 0)
return (error);