[totaltec]

First of all it is extremely cool that you created your own modifier!

I don't know of any examples where a modifier is passed a value. I'm sure it could be done, but you might have to modify:

    /**
     * Call for Flexy modifier from AView class
     *
     * @param string $callMethod Name of method to call
     * @param string $expr       Exression to modify
     *
     * @return string
     */
    protected function flexyModifierCall($callMethod, $expr)
    {
        $callMethod = 'flexyModifier' . ucfirst($callMethod);

        return method_exists($this, $callMethod) ? $this->$callMethod($expr) : '';
    }

Reading through the method above, I think it would have to have another argument added, like:
protected function flexyModifierCall($callMethod, $expr, $params = NULL)

Then you could pass it some parameters and use those in your call. But I am just not sure that it is wired that way. Probably I would just create a method that shortened the text with 2 arguments, value and length.