To change the fonts for the menu from the command line, type:
dtterm -xrm '*fontList: fontset'
where fontset is a font set specification. A font set specification can be specified by a full X Logical Font Description (XLFD) name list, a simple XLFD pattern, or an alias name. Note that a font set specification is determined by the locale that is running.
For example, to use a larger font except for the menu font, type:
dtterm -xrm '*fontList:-dt-interface user-medium-r-normal-l*-*-*-*:'
To use a smaller font except for the menu font, type:
dtterm -xrm '*fontList:-dt-interface user-medium-r-normal-s*-*-*-*:'