Using a spray can of "Cable Lube".
Since I mostly use a cable luber clamp, it needs a spray straw application.
I think the Cable Lube is made by PJ1 (something like that).
Also was using another spray in a green spray can (Motorex or MotoPro - can remember as it's gone now).
Way back, used to pull the cables and stick one end into the corner of a ziplok bag w/rubber-band to seal, hanging, with the lower end suspended into a can/pail. Then I poured some ATF into the bag and it would work its way through the cable into the catch container. I'd just let it hang overnight to ensure excess got through. Then remove and install back on bike. There was always ATF laying around and it worked better than nothing.
I've used teflon sprays, and the Bel-Ray 6 in 1 that Smokey 14 mentioned works good.