Although I've never played this game, I am Indonesian. So, I'll translate for you \o/
Registration:
On the main page, (
Emil Chronicle Online: Indonesia) click the left icon "Daftar Baru".
Then fill the form on the right hand side.
For the gender drop box, laki-laki = male, perempuan = female.
Your pin can only consist of 6-8 numbers.
Don't forget to tick the box next to "Saya setuju..."
Once that's done, you will get a congrats page. Click "Klik disini" to skip the redirecting process.
Then you'll see a log-in form on the left side, fill that in with your newly created ID/pass. It will take you to your WavePro Game Portal.
To download the ECO client you can just simply click Download > Client. (Top bar)
Before you can play ECO however, you'll need to 'activate' your game.
To activate ECO:
In your WavePro Game Portal,
click the 'Aktifkan' button under "Emil Chronicle : Belum Aktif"
Fill in the form (It's in English)
And voila! It should now say "Emil Chronicle : AKTIF"
Since my internet is capped, I didn't actually download the game so I dunno what happens next. (It also stopped me from uploading any pictures)
But if you want anything else translated I'd be happy to do so. We borrow quite a lot of English words, so it should be pretty easy to figure out what things are (compared to other foreign games)