The print action field in the dt configuration files should be modified to add the Hebrew text filter. For example, in the dtmail application, the print action in the file /usr/dt/appconfig/types/he/dtmail.dt should be:
ACTION Print { LABEL Print ARG_TYPE DTMAIL_FILE TYPE COMMAND WINDOW_TYPE NO_STDIO EXEC_STRING sh -c ' \ dtmailpr -p -f %(File)Arg_1% | /usr/lib/lp/postscript/convert_text -inputTextMode -text_mode_implicit -outputTextMode text_mode_visual -lineWidth 80 -inputLayoutDirection left_down -outputLayoutDirection right_down| mp -A4 -L he| dtlp -u %(File)Arg_1%;'}
The listed convert_text parameters will print right-aligned text right-to-left. To print text aligned to left, left-to-right replace the previous parameters with -lineWidth 80.