Setting serial speed/Baudrate dynamically?

[nappington]

We have multiple machines with both 9600 and 115200 Baud rates. I'm curious if there's a method by which I can set this dynamically in iPXE, either through autodetection (unlikely), or by changing the dhcp options.

SYSLINUX had a method by which we were able to set a dhcp option (pxelinux.configfile) for a machine with a specific Baud Rate - when it PXEBooted, the config file would read it (setting the first line as: SERIAL 0 {SERIAL})

Is there a similar way to do this in iPXE, or any other alternatives?