Traveling Software's LapLink-V and LapLink-Pro implement a "proprietary" 
eight bit parallel data transfer scheme.  In most cases, Traveling 
Software furnishes both a parallel and serial cable with their software.  
However, they also market one version of LapLink-V intended to be 
included in a hardware bundle which comes only with the serial cable.  
This version is full featured, and has all protocols for their serial, 
four bit (LapLink-III compatible) and eight bit data transfer.

Unfortunately, Traveling Software publishes only their serial and 
four-bit parallel interfaces.  The eight bit data transfer scheme 
appears to be an extension of the four bit method (That is, an eight bit 
parallel transfer cable can be used for four bit parallel transfer).  
Taking a trusted ohmmeter to an existing cable reveals the following 
pinouts:

        DB-25P      DB-25P          Printer             Cable
       Socket 1    Socket 2         Usage               Color
                                        Socket 1            Socket 1

          1           1*            Strobe              Brown
          2          15             D0                  Red
          3          13             D1                  Orange
          4          12             D2                  Pink
          5          10             D3                  Yellow
          6          11             D4                  Green
          7
          8
          9
         10           5             Acknowledge         Grey
         11           6             Busy                White
         12           4             Paper Out           Black
         13           3             Select              Brown/White
         14          14*            Auto Feed           Red/Black
         15           2             Error               Orange/Black
         16          16*            Initialize Printer  Lt.Blue/Black
         17          17*            Select Input        Lt.Blue
         18
         19
         20
         21
         22
         23
         24
         25          25             Common              White/Black

The asterisks indicate the lines that are added from LapLink-III, which 
supported only the four bit protocol.  Note also that the cable is 
bidirectional; either end can be plugged into either the source or 
destination machine.  The four bit version of this cable also matches 
Novell's specification for a parallel data link for their FileLink 
data interchange utility.

One good way to start building a LapLink-V cable is to purchase a 
standard parallel printer cable from your favorite computer store.  Then 
simply cut off the Centronics connector and use an ohmmeter or 
continuity tester to determine which wire connects to each pin on the 
connector.  The chart above indicates the colors for the cable which I 
used, which was purchased from MicroCenter.