The Collaborative International Dictionary of English v.0.48:

Catechetic \Cat`e*chet"ic\, Catechetical \Cat`e*chet"ic*al\, a.
   [Gr. ?. See Catechise.]
   Relating to or consisting in, asking questions and receiving
   answers, according to the ancient manner of teaching.
   [1913 Webster]

         Socrates introduced a catechetical method of arguing.
                                                  --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

catechetical
    adj 1: of or relating to or involving catechesis [syn:
           catechetical, catechetic]