The Collaborative International Dictionary of English v.0.48:

Individualize \In`di*vid"u*al*ize\, v. t. [imp. & p. p.
   Individualized; p. pr. & vb. n. Individualizing.] [Cf. F.
   individualiser.]
   To mark as an individual, or to distinguish from others by
   peculiar properties; to invest with individuality; to give
   distinctive character to; to make distinctive; to enable
   differentiation from others of similar type; -- of properties
   of things.
   [1913 Webster +PJC]

         The peculiarities which individualize and distinguish
         the humor of Addison.                    --N. Drake.
   [1913 Webster]

   2. to render (a product or service) suitable to each
      individual person by varying to some degree its
      characteristics; to personalize.

   Syn: personalize, individualize, make personal, make more
        personal.
        [WordNet 1.5]

   3. To consider individually; to mention each individual.
      [PJC]

WordNet (r) 3.0 (2006):

individualize
    v 1: make or mark or treat as individual; "The sounds were
         individualized by sharpness and tone" [syn:
         individualize, individualise]
    2: make personal or more personal; "personalized service" [syn:
       personalize, personalise, individualize,
       individualise] [ant: depersonalise, depersonalize,
       objectify]

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "individualize":
   analyze, anatomize, atomize, change, chop logic,
   descend to particulars, desynonymize, detail, difference,
   differentiate, discriminate, disequalize, disjoin, distinguish,
   diversify, divide, individuate, itemize, make a distinction, mark,
   mark off, mark out, modify, particularize, peculiarize,
   personalize, precise, quality, refine a distinction, segregate,
   separate, set apart, set off, sever, severalize, signalize,
   specialize, spell out, split hairs, vary