chainload EFI from alternate TFTP server

[eterle]

We use PXE boot to bring up a custom grub menu (pxelinux.cfg/default) when installing a new system. From this menu we can choose the OS which will then get installed over the network.

I now need to add the Solaris 11 to this menu, but it resides on a different TFTP server.
All I want this entry to say is: load this boot image ( grub2netx64.efi ) from that TFTP server.
I thought I could get away with something like:
kernel chain.c32 (or pxechain.com or pxechn.c32)
append <tftp_server_ip>::grub2netx64.efi (or tftp://<server_ip>/grub2netx64.efi)

But it seems I can't chainload (is that even the right term?) an efi image.
I looked into switching to grub2, but I have been thoroughly unable to find how to rewrite my menu items in grub.cfg so I gave that up. I couldn't even get the simple "localboot 0" to work.

Can iPXE be of help to me?
Thanks for your help.
D