libvirt users - Mar 2014 - Specify a disk image file which is on an iscsi target

Hello,
for my vm I'd like to specify a disk image which would be on an iscsi
target.
Currently, by using targets directly, I'd just specify the path in
/dev/disk/by-path/ip-192.168.1.2:3260-iscsi-iqn.myiqn

but how to specify a file which is actually INSIDE this path, ex.
/dev/disk/by-path/ip-192.168.1.2:3260-iscsi-iqn.myiqn/myVmImage.img ?

I saw that there is another path in /media/myHomeUser/anId but do this id
changes each time?