The cartos will fit the 901 threads. The problem is with airflow. 901's have a little hole in the side of the atty for air. Cartos get air from the bottom.
You can get an 'adapter' from vapor country but it adds about an inch to the overall length.
DSE-901 Cartomizer Adapter 6.99!!!
Your other option (if you're good with a dremel) is to carve a small groove across the center button and threads of your connector. You gotta be careful though. You could render the whole thing useless.
Thusly...
Make it look like this and you're good to go for 808's or GC cartos...
I should add... this will probably void your warranty...at least for the connector part of your chuck.
Edit #5: if you don't want to use greencig cartos and just KR808's you don't need the channel in the center button (808 already have that) you just need air through your threads, so you could just drill a small (very small 1/32") hole through the threads.