Catalysis of the reaction: 5beta-cholestane-3alpha,7alpha,12alpha-triol + 5 H+ + 3 O2 + 6 reduced  = (25R)-3alpha,7alpha,12alpha-trihydroxy-5beta-cholestan-26-oate + 4 H2O + 6 oxidized .
TEHC-NAD oxidoreductase activity