The eMac includes a user service door that allows access to the RAM, AirPort card, and clock battery. It's incredibly easy to remove.
It should be noted that these guides are written based on a late-model eMac (2005, 1.42GHz, DDR). They will differ slightly from the older model eMacs that use PC-133 RAM.
Lay the eMac screen-down on a flat surface. I've found it convenient to use a carpeted floor because the computer is so heavy.
Remove the single phillips #2 screw on the RAM door, and remove the door
The screw is captive in the door, so don't worry about losing it.