The time it takes to cook a cake in a rice cooker varies depending on the brand, model and capacity, and usually takes about 30-60 minutes. The exact time also depends on the recipe and ingredients you use. Here is a general step-by-step procedure:

Pour the beaten egg batter into the pre-oiled inner pot of the rice cooker.

Close the lid and press the "Cook" button to start cooking.

After about 20 minutes, open the lid and check the status of the cake. If the top is set, you can continue baking.

Every 10 minutes or so, test for doneness by inserting a toothpick into the center of the cake. If the cake is cooked through and the toothpick does not bring out a sticky batter when inserted, you can turn off the power.

Finally, wait for the cake to cool completely before removing and enjoying.

It's important to note that each rice cooker has different characteristics, so it's a good idea to check the instructions provided by the manufacturer before using it to make sure you're doing it correctly.