you could use a .bat file, with something like this in it:

java %*

and associate classes with it - of course if your class is in a package
you have problems
if you need to control the classpath and maybe which jvm you might use
something like:

J:\java\jdk1.4.2\bin\java -classpath myprojectlibs.jar %*

or you could make a specific .bat file  for each test condition you want,
like:

J:\java\jdk1.3\bin\java -classpath canvas.jar
com.qlt.canvas.fractal.equation.Test fractint,par %1 %2

etc etc.

I once wrote a batch file which asked me which jvm to run  with (but I
can't remember how I did it - too long in unix land I guess).
Stuffing around with exe  files is a level of complexity you don't need
(and you still have to sort out classpaths etc).