This message is on a wall in mission 6. To find it, bring up the map. Now hold the ~ key to teleport. Find the location (0190/46.0/0466) on the map and type lantfh.
The cave on mission 8 is shaped like the head of Max. To find it, activate the map. Go west and drop down onto the ledge in front of you. Head north and crouch to enter the passage.
Another hidden Ewok is in Mission 7. To find him, bring up the map. Now hold the ~ key to teleport. Find the location (-099/-51.0/0516) on the map and type lantfh. You'll find an extra life. Toss a thermal detonator north to blast open the wall and find the Ewok.
There is a hidden Ewok in Mission 4. To find him: Type laimlame. Jump off the opening right in front of you. Type lapogo. Turn and face the wall that you just jumped off. Turn right and and walk against the wall to the right. You will go into a small dark room. Go to the wall on your left. Walk up to it and hit the spacebar to open it, and you will find the Ewok.