wimboot from SYSLINUX menu?

[mangeek]

I work at a large university. We use iPXE to chainload to a SYSLINUX/PXELINUX menu via HTTP. From there, we usually use MEMDISK to load Linux or Windows installers.

What I'm hoping to do is change to booting the wims directly off the server. I can do it using the generic wimboot instructions, but not from the SYSLINUX menu. Any pointers on how to get that to work?

Here's our current process:

Native PXE pulls undionly.kpxe via TFTP (all DHCP points to load this iPXE binary)
(iPXE script embedded in undionly.kpxe
#!ipxe
imgfree
set 210:string http://server/ipxe/
set 209:string http://server/ipxe/menus/default\
set filename \${210:string}pxelinux.0
chain ${filename}

Which brings us into the PXELINUX menu. Invoking MEMDISK from there loads the payload into RAM via HTTP and boots it. I want to wimboot, though.