[pdftex] how to add pdf highlighting?

[Dave Brydon]

Hello.  We are using pdflatex to publish books with extensive highlighted 
text that extends sometimes over multiple paragraphs and across page 
boundaries.  We have not found a satisfactory way to do it.  By 
highlighting I mean putting a solid color background behind the text of 
sentences, starting at a given word and ending at some other word.  The 
highlight color should be contiguous from beginning to end, except  perhaps 
at paragraph breaks.
	PDF seems to have a highlight capability built in.  I wondered if there is 
some way with pdflatex to insert the pdf command to turn highlighting on 
and off?

Thanks very much,

Dave