Soft line breaks in XSL:FO output

Platform: DocBook XML 4.2,
	  DocBook XSL 1.60.1,
	  xsltproc 1.0.27,
	  fop 0.20.5

Is there a way to introduce soft line breaks into XSL:FO output?

I have two URLs in table cells, that breaks in this manner:
  ht-
  ttp://somemachine/path/to/some-
  where

And that looks a bit silly.

I can't make the columns wider, and I can't make the URLs shorter, and
I don't want to change the table.  It's a table that lists PUT and GET
URLs for different services.  Ie. like this:

 +------------------+----------+---------+
 |                  | GET URL  | PUT URL |
 +------------------+----------+---------+
 | Some desc.       |          |         |
 +------------------+----------+---------+
 | Some other desc. |          |         |
 +------------------+----------+---------+

Thanx!


- Steinar