That is still basically the process. You need to ensure that the arch options are being selected properly in your dhcp file, ex:

if option arch = 00:07 { filename "uefi/shimx64.efi"; next-server X.X.X.X; } else ...

Otherwise, your going to get the wrong arch/filename.

It is similar to HTTPS, but the arch = 00:10 for x64 and it needs:

option vendor-class-identifier "HTTPClient";

Then put the URL in the filename field.

Finally just put the usual bios/pxe stub in the last "else"

Of course, your distro should provide a PXE capable grub/kernel/initrd, which you then toss on the TFTP/HTTPS (or HTTP then you don't have to deal with certs) server in the path provided.