I'm an Eglu user and have transitioned one group. Few tips that worked for us.
- Take out the roosting rack and put bedding in the bottom tray that matches whatever's in their brooder. They like to sleep in a puddle for a few weeks anyway before learning to roost.
- When you bring them out to the pen for field trips, put them into the Eglu through the back. Give them a minute, then open the front door and let them walk down into the pen.
- Encourage them to explore the Eglu during the day. Open it up, offer some treats inside, etc.
- When the big day came, we had to literally stuff them into the coop one at a time. Two people makes this much easier. They cried quite a bit, but eventually settled down for the night. The next night, 3 out of 4 went in on their own. We had to help the last one for a couple nights, but always gave her a chance to figure it out on her own.
Don't put food and water in there. You should only shut them in if it's bed time. Like you said, the Omlet's not a traditional coop and it's cruel to keep them in there longer than they need to be.
Good luck! I'll be training myself this week with our new group.