chakra linux and easybcd

BURG is not supported by EasyBCD at this time. GRUB, GRUB2, FreeBSD are all supported but nothing more when it comes to Linux Distros if I remember correctly.

I heard it was a fork of Grub2 so I choose Grub2.
But now I see a message of Grub4Dos and a grub prompt.

Anyone a idea how to proceed now.

EasyBCD creates these when you add the entry. Since it isn't GRUB or GRUB2, you will have to go to Chakra's website and find out how they allow it. Till we can get support for BURG there is not going to be anything we can do to help.
You'll need to use NeoGrub to boot into it, but you'll have to do the configuration yourself.