You should modify the file fop.properties to have good path : jlatexmath-0.9.1, fop 0.95 and xmlgraphics-commons-1.3.1 are required to compile jlatexmath-fop. In fact the version 0.95 is essentially required to handle embedded fonts which are in jlatexmath.jar.

After the version 0.9.4, the plugin can be used (and must be compiled) with fop 1.0 and xmlgraphics-common-1.4.

Put jlatexmath-fop.jar and jlatexmath.jar in your fop/lib or in a directory known by fop. 

To see it in action, go to the directory examples and read the README.

Have fun ! 

Calixte (calixte@contrib.scilab.fr) 