On my gwt project. i have a script that call the dictionary:
i
Basically you inject the script element in your onModuleLoad():
Element head = Document.get().getElementsByTagName("head").getItem(0);
ScriptElement sce = Document.get().createScriptElement();
sce.setType("text/javascript");
sce.setSrc("conf/iw_dictionary.js");
head.appendChild(sce);
The browser will automatically load it as soon as it's injected.