Being possibly the worlds laziest mechanic, I years ago bought a spare dust cap for my Campagnolo Record pedals. I drilled and tapped it, and fitted it with a zerk grease fitting. Whenever I think it's time, I switch caps, and pump grease through the pedal clearing dirt and old grease from the crank end. (the old grease on the closed end is clean so I don't need to worry about transferring it to the other bearing)

The only drawback is that grease will continue to weep from the pedal for a while, but I just wipe it up. These pedals have 10s of thousands of miles on them and have never been opened for adjustment or service of any kind.

If your pedals have threaded dust caps you can do the same, but it may be difficult with press fit caps, unless you find a way to keep them on against the pressure of the grease. It might also be possible to feed grease slower and rotate the spindle to help it flow down the spindle at lower back pressure.

BTW- all the pedals on my various bikes are set for greasing without dis-assembly in the same way, except for my commuter which has old SunTour grease guard pedals.