All you should need to do to build the executable is type @make

To run xlock a symbol needs to be defined, for example:
 
XLOCK:==$H268SYSEXE:XLOCK
 
where H268SYSEXE is a logical name pointing to the directory where XLOCK.EXE
resides. The '$' after == means this is a foreign command and VMS makes the
command line available to the program.

worm may look a bit strange, since the scaling is wrong.

-allowroot only works if you have SYSPRV enabled which is a bit limiting.

The XLock file normally in /usr/lib/X11/app-defaults needs to be in the
directory DECW$SYSTEM_DEFAULTS on VMS systems and be called 'DECW$XLOCK.DAT'.