If you don't have already installed 
Knot2000 (K2K), Version 1.3.1 
by M.Ochiai and N.Imafuji
(http://amadeus.ics.nara-wu.ac.jp/~ochiai/freesoft.html)
please:

1) All files from downloaded K2KLK.zip extract 
in Mathematica directory

WolframResearch/Mathematica/4.0 (or 4.2).

WinZip will extract them automatically 
it in the subdirectory K2K1_3_1.

2) Open in Mathematica the file K2K.nb containing 
the program KNOT2000 (K2K) or the file K2KC.nb 
containing KNOT2000 (K2K) and its extension LinKnot(K2KC)
by S.Jablan and R.Sazdanovic. The corresponding 
manuals are given in the files ManualK2K.nb and ManualK2KC.nb

If you already have installed 
Knot2000 (K2K), Version 1.3.1 
by M.Ochiai and N.Imafuji:

1) All files from downloaded LinKnot.zip extract in the 
Mathematica subdirectory K2K1_3_1, replacing some old files by new ones.

2) Open in Mathematica the file K2K.nb containing 
the program KNOT2000 (K2K) or the file K2KC.nb containing 
KNOT2000 (K2K) and its extension LinKnot (K2KC). The 
corresponding manuals are given in the files ManualK2K.nb and ManualK2KC.nb

From the address 

http://amadeus.ics.nara-wu.ac.jp/~ochiai/freesoft.html

you can also download the Mathematica package 
MathTangle by M.Ochiai and N.Imafuji.