The lookup control is not going to expose anything on the server side to do what you want... you'll have to manhandle the DOM with client-side Javascript.
This code was written for 7.5.4 (Ext.js not Dojo), but it might be a step in a direction (hopefully the right one!). On page load the lookups are built in JS and named "[clientID]_luobj", this object contains all the lookup methods and properties. The "initGrid" function is fired when the client clicks the lookup control, which builds the lookup UI in the DOM. We extend this method on the lookup instance: first we call the prototype method, then add our extra junk (in this case, sort the grid). For dojo you'd want to use "mixin" instead of "apply", and "dojo.ready" instead of the jQuery "$(window).load(...)". I use Chrome developer tools to wade through the available members.
This is a C# snippet set up for onLoad. You'll need it to run on every repaint.
// create the javascript
string script = @"
$(window).load(function() { // this fires after lookups (luobj's) are built
var obj = " + lookupName.ClientID + @"_luobj;
obj.initGrid = function (seedValue, reload) {
LookupControl.prototype.initGrid.apply(this, [seedValue, reload]);
this.getGrid().getNativeGrid().getStore().setDefaultSort('Name');
}
});
";
// register the script for pageload
ScriptManager.RegisterStartupScript(Page,Page.GetType(),"LookupSort",script,true);
Sorry this is not a complete solution.
