Yes it should work.
The IDS-4250-XL is fully supported by version 6.0(1).
Execute "show int brief" and you should see entries for:
GigabitEthernet0/0
GigabitEthernet0/1
GigabitEthernet2/0
GigabitEthernet2/1
(the last 2 being the interfaces of the XL card)
If you don't see the last 2 interfaces, then try rebooting the sensor, and check again.
If they still don't show up, then shutdown the sensor, open up the chassis, pull the card out, put the card back in (to ensure a good connection), and power back up.
If the chassis has been moved it is possible the card became unseated and so the software can't detect the card.
If still no luck, then try a complete re-image. Copy off your config using "copy current ftp://user@//directory/configfilename
Then execute "conf t" and "recover app".
It will re-install 6.0. When the installation completes, then login with cisco and default cisco password. And execute "show int brief" again to see if this time the card is recognized.
If the card is still not recognized then contact the TAC you may have to RMA the hardware.
