Yes it is possible to get but not very easy. If you go here
https://jpn00.konami.co.jp/products/mgs2/english/mr/ the clear code web site you can search with the record sorter. Search the extreme and clear times and you will ussually find 1 or 2 on there. In order to get it I believe you have to have
Extreme difficulty
under 3 hours
8 saves or less
Kill knowbody even bosses (except metal gears and harrier)
only 3 Alerts (the ones that cannot be avoided)
No radar
No special items
I think that is it, If not someone can correct me. I have not recieved it yet but plan to this weekend. Trust me it is not easy.