I think the standard method it to try and lever them up, however I struggled with that too. I've used a small bottle jack under the bottom of the damper plate mount (on the stub axle). Lifted it no more than 2-3mm but helps to get the grease through.

"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10