@Mark_Bailey is quite right. But a while ago, I did some 'Lunch and Learn' presentations on 'Computer Intensive Methods', and I took this as one of the examples. Unzip, and look for 'Similarity of Distance Matrices' in the JRN that you get. The JSL could be easily repackaged as an add-in.
But bear in mind that this material is nearly ten years old (!?), and there are almost certainly better ways in JMP now for many of the topics covered.