Sorry man, This BIOS can not be modded as of now. You might want to try getting an Intel Network card with a netboot ROM embedded and try it that way.
Just some precision about my motherboard D2700DC. First i've test with this tutorial with the string "Dell System" -> it doesnt work with Dell XP sp3 cd and nothing view on Slik tool kit. Then i've tried with the string "Dell Computer" and Put the string on Manufacturer,Product (system) and Manufacturer (chassis) and now all works like a charm (slik toolkit ok). To add slic2.1 cert i've used OA2INTEL that was present on some pack (just search), it works but just stay present after bios update (with same version, im going to try with older then newer to see). Long life to MDL forum.