The handbook and manpages for linprocfs/linsysfs don't describe how linprocfs/linsysfs should be mounted via /etc/fstab. I used the following incantation and it worked with mount -a after the kld's had been loaded and my CentOS 6.x base had been installed.
linproc /compat/linux/proc linprocfs rw,late 0 0
linsys /compat/linux/sys linsysfs rw,late 0 0
I found this in the linprocfs(5) man page, though I can't be certain it was there when you sent this in!