How to make squashfs of 3.1 with mksquash 4.0

[Eric Zhong]

I have to make a install.img for F10 on F13
Squashfs Version : F13 = 4.0 ; F10 = 3.1
I can't mount 4.0 on F10.
so How can i make a version of 3.1 on F13 ? Are there any options ?