Mknod return "Operation not permitted"

[sinlam]

Hi,
  I am currently facing a problem where MKNOD returned "Operation not permitted" when a user is logging in. I use OsxFuse 2.4.2 and the 'loopback' example. My Mac does not have auto log in. When seeing the log in UI, I ssh to my Mac from another machine, then execute the following command to mount the /tmp dir. 

>sudo ./loopback /tmp -omodules=threadid:subdir,subdir=/.tmp -oallow_other,native_xattr -d

Then log in my Mac.
I realize that after user login, he cannot see his Dock; this is due to OsxFuse MKNOD function always return "Operation not permitted" on '/tmp' path. Is there any way to overcome this problem? I would like to do processing on this /tmp dir.
Thanks for any information!

Regards,
Sin Lam

[sinlam]

I have some update on the problem but I still don't know how to solve the problem. On further investigation, I notice that when a user logins to his desktop, there is X11 socket created on /tmp directory, and the socket call arrives in MKNOD function (non-FIFO mode), where it fails with "Operation not permitted". There is why I got blank desktop with no dock.

I also tried without OsxFuse by changing the /tmp directory to soft link to another dir, say /mytmp. I also got the same problem with blank desktop when the user is logging in. Can anyone suggest how can I change /tmp dir on Mac OS X?
Is there any special extended attributes that I need to add to the new temp directory?

Thanks for any information!