We made them once when I was a chef and worked in Singapore, we got pre-made nes from a shop, but ran out, we had to make 500 and were short, we improvised the recipe from the packages, it is alot like making crepes, but you add rice flour and wheat flour/starch, eg whites only, oil and water, you make a paste as thick as pouring cream and cook them very lightly in a pan, not browning them, I have done this for Italian dishes like Cannelloni, and eastern european ones where you stuff the crepe with sauerkraut and mushrooms, bread them and pan fry.
Just make sure the heat under the pan is very low so the set up and when yu turn them just 10 second on the other side, lay on a tea towel and cool, trim if you want a square type, and roll the lumpia, then fry, I would chill them on a piece of plastic wrap, lightly oiled to prevent sticking before you cook them in the oil, they will not be as crisp as the packaged ones but a very good substitute, you can do the same for spring rolls only use the whole egg.

