It's not just a case of more pressure etc, they are easy to do with patience, no amount of extra pressure will hurry them up, it will have the opposite effect.
Firstly DON'T use WD40, this dries things out, use regular grease, on the bush and inside the "cup", make/borrow etc a puller so you can pull them via the centre hole, the secret is not to apply too much pressure, just a little at a time, you will see the bush creeping slowly, it needs time to deform slightly as the end tries to get through the hole, extra pressure will simply jam it up, using a wide bladed screwdriver help the lip come through the hole, I would say around 10-15 mins per bush will see them easily go in, keep adjusting the pressure as you go but only slightly, you'll soon see how much works best.
I made a tool up from some 90 degree angle 4mm thick by about 2" x 2", with this I can fit them or remove them ON CAR, no need to take the beam off, I just used a 100mm socket, and some threaded bar/nuts to wind in, obviously not every ones got 100mm sockets so improvise with something as best you can.
tabetha