since the original functionality was promoted and will be part of the next version. i added a new functionality. it might be the case that you have issues while prototyping. if so, please report them to the mailing list. anyway, normally you would have to remove extval from the classpath so that you can continue your work. that's due to the zero config approach of extval. you can deactivate it via api's but now you have a further possibility.
the current trunk version (= the next milestone) allows to provide a custom implementation of the extval-context. that allows to introduce alternative approaches e.g. using a dependency injection framework like spring and google guice for internal tasks as well as registering artifacts via dependency injection.
it also allows to mock the extval context. so you can deactivate all/specific features easily. an example is available at [1]. since you have to configure a custom extval-context manually (the class provides the needed information to do it), you can add it to your project permanently. if you would like to check something without extval, just activate the config and afterwards you can remove it again. as mentioned before, it also allows to deactivate specific features easily without using web.xml context-parameters.
anyway, normally you shouldn't have problems. if you find issues, please report them as soon as possible.
[1] http://code.google.com/p/os890/source/browse/trunk/java/web/jsf/extval/prototyping/org/apache/myfaces/extensions/validator/custom/DevExtValContext.java
