Yes. Both the LaserWriter IINT and the the LaserWriter IINTX can be set to
PostScript interactive mode via PostScript.
Use the PostScript procedure that selects PostScript interactive mode. Type
"executive", followed by a return or line-feed, and the LaserWriter will be in
interactive mode.
Control-D or the PostScript "quit" operator causes the LaserWriter to go back
to batch mode.
For more information, see pp. 289-290 of the "PostScript Language Reference
Manual", also known as the "Red Book" (Addison-Wesley, ISBN #0-201-10174-2).