An LZ4 compressor PR was accepted by wiredtiger/wiredtiger and is coming to mongodb/mongo sometime soon.
Patches to mongod and the scons build are needed to integrate this wiredTiger storage engine compression engine.
A patch against 3.0.0-rc11 is attached to this ticket, but patches both the vendored wiredTiger library as well as mongod and the scons build. The src/third_party/wiredtiger portions will not be needed once a newer wiredTiger library is imported.
Ping me when/if ready to adopt this feature and I can produce a new patch just for the scons build and mongod.