i've got poppassd working
given the following pwserve-5-osf1.install.sh
and poppassd.c.diff
(findpty is based on the one i found in /usr/pkgsrc/samba2)

comments welcome..,
~n

pwserve-5-osf1.install.sh:
#!/bin/csh

# extra logging
echo "local2.err   /var/adm/poppassd-log" >> /etc/syslog.conf

# create log dir/file
mkdir /var/adm
touch /var/adm/poppassd-log

# create /bin/passwd
cp /usr/bin/passwd /bin/passwd
chown :bin /bin/passwd
chmod u+s /bin/passwd

# add to inetd.conf & services
echo "poppassd stream tcp nowait root /usr/local/bin/poppassd poppassd" >> /etc/inetd.conf
echo "poppassd     106/tcp" >> /etc/services


poppassd.c.diff:
*** poppassd.c.orig	Mon Jul 12 15:45:41 1999
--- poppassd.c	Tue Jul 13 14:29:25 1999
***************
*** 154,159 ****
--- 154,160 ----
      "Changing password for *\n*'s Old password:",
      "Changing password for *\nOld password: ",		/* for Ultrix */
      "Changing password for *.\n\nOld password:",	/* for OSF/1 */
+     "Changing local password for *.\nOld password:",    /* for NetBSD */
      ""};
  
  static char *P2[] =
***************
*** 171,181 ****
--- 172,184 ----
      "\nVerify: ",					/* for Ultrix */
      "\nWarning, only the first 8 characters of the password are significant.\nVerify: ",						/* for Ultrix */
      "\nRetype new password:",				/* for OSF1 */
+     "\nPlease enter a longer password.\nNew password:", /* for NetBSD */
      ""};
      
  static char *P4[] =
     {"\n",
      "NIS entry changed on *\n",
+     "\nRetype new password:",                           /* for NetBSD */
      ""};
  
  
***************
*** 199,205 ****
  #ifdef ULTRIX
       if (openlog ("poppassd", LOG_PID) < 0)
  #else
!      if (openlog ("poppassd", LOG_PID, LOG_LOCAL2) < 0)
  #endif
       {
  	  WriteToClient ("500 Can't open syslog.");
--- 202,209 ----
  #ifdef ULTRIX
       if (openlog ("poppassd", LOG_PID) < 0)
  #else
!      openlog ("poppassd", LOG_PID, LOG_LOCAL2);
!      if (0) 
  #endif
       {
  	  WriteToClient ("500 Can't open syslog.");
***************
*** 418,423 ****
--- 422,457 ----
        return(0);
     }
  }
+ /*******************************************************************
+ safe string copy into a known length string. maxlength does not
+ include the terminating zero.
+ ********************************************************************/
+ char *safe_strcpy(char *dest, char *src, int maxlength)
+ { 
+     int len;
+ 
+     if (!dest) { 
+ /*        DEBUG(0,("ERROR: NULL dest in safe_strcpy\n")); */
+         return NULL;
+     }
+   
+     if (!src) {
+         *dest = 0;
+         return dest;
+     }
+ 
+     len = strlen(src);
+ 
+     if (len > maxlength) {
+ /*             DEBUG(0,("ERROR: string overflow by %d in safe_strcpy [%.50s]\n",
+                      len-maxlength, src)); */
+             len = maxlength;
+     }
+ 
+     memcpy(dest, src, len);
+     dest[len] = 0;
+     return dest;
+ }
  
  
  /*
***************
*** 433,462 ****
   * Modified by Norstad to remove assumptions about number of pty's allocated
   * on this UNIX box.
   */
! findpty (slave)
! char **slave;
! {
!    int master;
!    static char *line = "/dev/ptyXX";
!    DIR *dirp;
     struct dirent *dp;
  
!    dirp = opendir("/dev");
!    while ((dp = readdir(dirp)) != NULL) {
!       if (strncmp(dp->d_name, "pty", 3) == 0 && strlen(dp->d_name) == 5) {
!          line[8] = dp->d_name[3];
!          line[9] = dp->d_name[4];
!          if ((master = open(line, O_RDWR)) >= 0) {
!             line[5] = 't';
!             *slave = line;
!             closedir(dirp);
!             return (master);
!          }
        }
!    }
!    closedir(dirp);
!    return (-1);
! }
  
  /*
   * writestring()
--- 467,517 ----
   * Modified by Norstad to remove assumptions about number of pty's allocated
   * on this UNIX box.
   */
! 
! /* static int findpty(char **slave) */
! int findpty(char **slave)
! { 
!   int master;
! #if defined(SVR4) || defined(SUNOS5) 
!   extern char *ptsname();
! #else /* defined(SVR4) || defined(SUNOS5) */
!   static char line[12];
!   void *dirp;
! /*  char *dpname; */
     struct dirent *dp;
  
! #endif /* defined(SVR4) || defined(SUNOS5) */
!    
! #if defined(SVR4) || defined(SUNOS5)
!   if ((master = open("/dev/ptmx", O_RDWR)) >= 1) {
!     grantpt(master);
!     unlockpt(master); 
!     *slave = ptsname(master);
!     return (master);
!   }
! #else /* defined(SVR4) || defined(SUNOS5) */
!   safe_strcpy( line, "/dev/ptyXX", sizeof(line)-1 );
! 
!   dirp = opendir("/dev");
!   if (!dirp) return(-1);
!   while ((dp = readdir(dirp)) != NULL) {
!     if (strncmp(dp->d_name, "pty", 3) == 0 && strlen(dp->d_name) == 5) {
! /*      DEBUG(3,("pty: try to open %s, line was %s\n", dpname, line ) ); */
!       line[8] = dp->d_name[3];
!       line[9] = dp->d_name[4];
!       if ((master = open(line, O_RDWR)) >= 0) {
! /*        DEBUG(3,("pty: opened %s\n", line ) ); */
!         line[5] = 't';
!         *slave = line;
!         closedir(dirp);
!         return (master);
        }
!     }
!   }
!   closedir(dirp);
! #endif /* defined(SVR4) || defined(SUNOS5) */
!   return (-1);
! } 
  
  /*
   * writestring()
***************
*** 512,517 ****
--- 567,577 ----
  
       if (!expect(master, P4, buf)) return FAILURE;
  
+      if (strcmp(buf, "\n") != 0) {
+         sprintf(pswd, "%s\n", newpass);
+         writestring(master, pswd);
+         if (!expect(master, P4, buf)) return FAILURE;
+      }
       return SUCCESS;
  }