Need help with PXEBooting

I have a Synology NAS that works well for EVERYTHING I need it to do, except one small thing that I WANT it to do and I can't figure out.

PXE-booting in a mixed BIOS/UEFI environment. (Meaning, I have VMs that are BIOS-based, and physicals that are either BIOS or UEFI). The Synology is the netboot/TFTP/PXEBoot server, and my DHCP is dnsmasq on my router (Tomato).

I'd like to set up my Synology netboot environment to provide a menu of Linux installers (ISOs) to either BIOS type. I can start with 64-bit installers of Arch and Centos and scale out from there once I have the config formats down.

So far, I've run across Netboot (sourceforge, bleh!), syslinux (which I think I need to get the Arch version of the binaries for PXE to actually work), and possibly Grub2 (which I'm familiar with on local installs, but not for PXEbooting). I've managed in the past to get lpexlinux.0 working for BIOS, but that won't work for UEFI.

Any ideas how to get this going?

(Cross-posting from /r/synology for more exposure/help from you experienced Linux guys/gals. Hope the mods don't mind..)