I guess necrons naturally suffer boarding based lists due to their low ship unit count. I would also like to see them buffed in base speed and damage a little bit.
As for your question, your best bet is probably to use escort to scouts, and every single CD of intertialess drive to keep distance.
If you time your starpulses well you can utterly erase any orndance around you. If timed well you can entirely negate a boarding party. Then try to do your best to recrew if you get hulked.