Silverhawk- I qoute from the Boeing FCTM for the 737, Revision 2 dated 31 Oct 2002, Page 4.88:
" Asymmetrical reverse thrust MAY be used with one engine inoperative. Use normal reverse thrust procedures and techniques with the operative engine. If directional control becomes a problem during deceleration, return thrust lever to reverse idle detent."
Also reverse thrust is not taken into account for you landing distance certification.
Hope this helps.
Cheers
