Thanks Frank, for your response.
I have uploaded a patch for isi2dataset.cpp
http://gdal.googlegroups.com/web/isis2dataset.patch
this patch add new functionalities :
detached dataset with using the pointer object key :
^QUBE = "data.xxx"
^QUBE = ("data.xxx")
^QUBE = ("data.xxx", nnn)
^QUBE = ("data.xxx", nnn <BYTES>)
regards