Here is a handy little tool you can add to your toolbox for about two dollars.
You can buy these at a Model Airplane Store; they are made for fueling those tiny engines used in model aircraft and cars.
Made from clear plastic, they make great little grease guns. The plunger pulls completely out, and you can place oil or grease inside the cylinder, and replace the plunger.
The curved spout is small enough at the end to fit in the tiny hole in the side of your hubs.
You could also drill a small hole in your pedal dust caps to lubricate the pedals. The great thing is, you don’t have to disassemble the part.
After greasing your hubs in this way, take a rag or paper towel with you on your next ride. The surplus grease will ooze out of the side of the hub, and start traveling along the spokes. Needless to say, you should wipe this off before it reaches the rim.