Buy yourself a hand pumped grease gun and an injector nose fitting
of some kind that fits on the end of the flex hose.
http://www.alemite.com/catalog/detai..._guns_adapters

Remove the rubbers if you can (a lot of them you can), and rinse it
out by soaking it in kerosene or mineral spirits. Regrease as best you
can by injecting grease into the gap around the interior bearing.
A lot of it is gonna leak out around that, depending on how well you
can plug up the places where you're not actually doing the injecting.

If you're lucky, you can coax some grease down the shaft to the
exterior bearing. They're not all made to be serviceable.

Finally, clean off all the grease that's leaked out to the exterior surfaces.

Or buy some new pedals.