If an Osprey found itself unable to rotate its engines to vertical, what would be the emergency procedure for landing?
The Bell Helicopter V-22 Guidebook covers survivability in Appendix 1.
Specifically it refers to

Redundant Fly-by-Wire Controls
Redundant Electrical Power
Redundant Hydraulics Swashplate
Actuator Armor

implying that this possibility has been engineered to a minimum.
Nevertheless, the premise of your question is that it's occurred, so further on in the same section we see

V-22 crashworthiness is a function of design. Heavy components,  such
as the engines and transmissions, are located away from  the cabin and
cockpit area. The proprotors are designed to fray or  “broomstraw”
rather than splinter on impact with the ground. The  energy-absorbing
landing gear system is designed to attenuate  most of the energy for
hard landings up to 24 fps. The wing is  constructed to fail outboard
of the wing/fuselage attachment in a  manner that absorbs kinetic
energy and ensures the cabin area will  not be crushed, thereby
protecting the occupants. An anti-plow  bulkhead prevents the nose
from digging in on impact, and the  fuselage provides a reinforced
shell that is designed to maintain 85%  of its volume during a crash.
Aircrew and embarked troops receive  additional protection from
crashworthy seats that stroke vertically to  absorb energy

(my emphasis)
Since the aircraft is still flying, I'd head for the nearest decently equipped airfield, conduct a normal fixed wing approach and land, trusting that the rotors will sweep a nice clean path along the runway instead of peppering the fuselage with shrapnel. I'd probably take the precaution of cutting power early to reduce the kinetic energy in the rotors before they hit the ground.