Hello Junkai,
Here is some info that I got from the insect board regarding elpahus quite a few years ago. I also did talk to the guy and he seemed legit but you never know. He said he had many generations of elpahus. Here is what he wrote on the board. Not sure it will be helpful but who knows. I didn't really try the cooling thing because it seem like too much effort. I don't like to breed beetles that need extra heat or cooling. I didn't have much of a problem getting eggs and larvae to adult from wild caught females but when they became adults and I mated them, the females didn't lay too many eggs. I think about 6. So after that I pretty much just gave up and figured I needed to do the cooling thing he mentioned and I wasn't going to do that. Here's his post:
Lucanus breeding method by Bugman
Hi everyone
I would like to tell you how I breed species of the genus Lucanus:
It is very important that you can fill at least 25 cm (10 inches) of substrate into your breeding container.
I put 5 cm (2 inches) of earth on the bottom and I lay big pieces of white rotten wood on it. Then I put about 10 cm (4 inches) of Flake Soil (fermented wood) on this. The rest is filled up with humus and rotten leafs. (4 inches) It should be kept humid and cool at about 15-18°C.
I feed the beetles with beetle jelly.
After the beetles die, I wait another few weeks and search for larvae. Searching for eggs is rather dangerous because they are very sensitive to pressure.
I keep each larva in a container of 500 ml - 1 litre (16-32 oz) with pure Flake Soil. A japanese friend said, that protein is not necessary to get big imagos. The beetles normally hatch after 2 years and become active during early summer of the third year, when they are kept at 15-18°C. When they are kept to warm the larvae could die or you will get small beetles.
Read more:
http://insectnet.proboards.com/thread/3047/method-breeding-lucanus-species#ixzz4igPBN063