Would anyone happen to know how to go about setting the
character attributes (bold, italic, ...) for a subset of
the characters within a string?

A particular example might clarify.
Suppose cell A10 contained the string: Mary
Suppose further that I wish to set the contents of cell C20
with: =CONCATENATE("I want ",A10," to go to the store.")

Now, how might I go about having the string copied from A10
take on bold or italic characteristics? I don't want to have
to place it in a separate cell and adjust the cell widths for
different length words...

A search of Excel's standard built-in functions didn't turn
up anything helpful, at least to my eye.

Any clues?