Sandpaper and elbow grease? Is a belt sander too risky? I've been using a little block of wood and some 60 grit to hand sand the little doohickies off. What's your preference?

For hand tanning at home,I sprinkle the leather side with corn starch and use a sanding block with coarse sandpaper to cut the "bloom". I fold up a towell for padding under the skin.The corn starch helps the sandpaper cut.
Use light pressure on thin skins or thin parts of skins.You can be pretty agressive on thick skins or thicker parts of other skins.
I find a circular motion will cut the heavier bloom better,then finish from center towards the skirt.