unfortunatly not. Drain life, siphon life, and death coil are all damage spells first off and healing is a bonus. It would be nice if healing gear worked, but as it is we have to many people complaining about warlocks being over powered.
Just imagine if we could stock up on healing gear which usually has a higher stat than just plain damage gear. Ex: 2 lvl 70 belts, one gives + 30 spell damage, the other gives +45 healing. With a little effort at 70 we could get healing easily past 1,000. people wouldn't be complaining about fear anymore though.
Plus if we stock up on it and add in fel armor there could be a chance we could tank/heal for regular instances.
It would be cool, but there's no chance it'll ever happen.