As you are probably aware, CompiledScript is deprecated; you should use CompiledBase instead. This describes how to convert.
You probably call updateVars in 3 places; index page, index item, slide. These must be replaced with a series of statements get("variablename"). You could create a single method "updateVars" that gets all the variables; I prefer to just get the variables that I need.
CompiledScript changes some variables from null to 0. You need to do this as well.
David said that the conversion "should be a 1-minute operation." I am flattered by his high opinion of my programming skills.
This is how I did it.
You may need other variables. If any variables are missing, you will get compilation errors (you do compile your Java don't you?).
You may not need all these variables, in which case Eclipse or NetBeans will warn you that the variable is not used (you do use an IDE don't you?).
Depending on your class structure, you need to declare each variable as private, protected or public.