The Collaborative International Dictionary of English v.0.48:

Orchestration \Or`ches*tra"tion\, n. (Mus.)
   The arrangement of music for an orchestra; orchestral
   treatment of a composition; -- called also instrumentation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Instrumentation \In`stru*men*ta"tion\, n.
   1. The act of using or adapting as an instrument; a series or
      combination of instruments; means; agency.
      [1913 Webster]

            Otherwise we have no sufficient instrumentation for
            our human use or handling of so great a fact. --H.
                                                  Bushnell.

   2. (Mus.)
      (a) The arrangement of a musical composition for
          performance by a number of different instruments;
          orchestration; instrumental composition; composition
          for an orchestra or military band.
      (b) The act or manner of playing upon musical instruments;
          performance; as, his instrumentation is perfect.

   3. The act of using instruments to measure or control the
      behavior of an object, as a patient in a hospital or a
      machine being tested while under development.
      [PJC]

   4. The act of furnishing or attaching instruments to/
      [PJC]

   5. The set of instruments included in a system; as, a
      harvester with modern instrumentation.
      [PJC]

WordNet (r) 3.0 (2006):

instrumentation
    n 1: an artifact (or system of artifacts) that is instrumental
         in accomplishing some end [syn: instrumentality,
         instrumentation]
    2: the act of providing or using the instruments needed for some
       implementation
    3: the instruments called for in a musical score or arrangement
       for a band or orchestra
    4: the act of arranging a piece of music for an orchestra and
       assigning parts to the different musical instruments [syn:
       orchestration, instrumentation]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "instrumentation":
   adaptation, agency, agent, appraisal, appraisement, approximation,
   arrangement, assessment, assize, assizement, calculation, channel,
   computation, correction, determination, estimate, estimation,
   evaluation, gauging, harmonization, industrial instrumentation,
   instrument, instrumentality, intonation, mean, measure,
   measurement, measuring, medium, mensuration, metric system,
   ministry, missilery, modulation, orchestration, organ, phrasing,
   preparation, quantification, quantization, rating, resolution,
   rocketry, setting, solution, survey, surveying, suspension,
   telemetering, telemetry, tone painting, tooling, transcription,
   triangulation, valuation, vehicle