It would be very nice if DHCP could set specific options depending on MAC-address. In our case we have some Snom-phones which expect the TFTP-server option to be in this weird format:
"http://provision.example.com/somewhere/{mac}", whereas the Linksys PAP2 expects the more conventional "provision.example.com".
In dnsmasq.conf, this is configured as follows:
dhcp-mac=snom,00:04:13:*:*:*
dhcp-option=66,"provision.example.com"
dhcp-option=snom,66,"http://provision.example.com/somewhere/{mac}"
Hopefully RouterOS could do it with a more human-friendly syntax.