If you go with the steel wool and vinegar - get the steel wool to
rust first. It's iron oxide that reacts with the acetic acid, the
result reacting with tanin (sp?) in the wood (naturally
occuring in oak - and, as noted, in tea) to produce a dark blue
to black. It's rust you're after to put in the vinegar - any
old rust - rusty nails, cast iron . . .

You might also look into India Ink.

Why one would "ebonize" pear wood is a mystery but . . .

charlie b