If you want this for viewport previewing, turn on “Onion Skinning” on the object you want to ghost (Misc tab). The controls for the #skins and such is in the display options, Scene tab.
You may have to beware an outstanding bug with the onion skinning, which hides the current frame when trying to view “full deformation”… Is that still ongoing?
Friedasparagus : Thanks for the heads-up, it seems the bug you talked about is still around, it hides the current frame if “full deformation” is on. But I`ll survive hopefully