What you're really looking for, is SharePoint 2010 Fluent Ribbon API. It is a Codeplex project, which simplifies work with ribbon. It has in-depth documentation, including huge amount of samples and screenshots.
The only bad thing about this solution, is that you should rewrite your XML ribbon definition to FluentRibbon ribbon definition. But code definitions are much more flexible, and also FluentRibbon provides some extra features: simplified syntax, full-length documentation and qualitative validation, so IMO, it's worth it.
In your case, the resulting code will look like this (inside feature receiver class, in FeatureActivated method):
var myTab = new TabDefinition
Id = "MyTab",
Title = "My tab",
// etc, create your definition here...
// instantiate RibbonCustomAction class
var ribbonCustomAction = new RibbonCustomAction();
// add one or more ribbon definitions, which will be deployed
// in same scope.
// RibbonCustomAction acts like a container for such definitions.
// Let's provision our custom action
// receiverGuid is a random constant Guid, which must be unique
// in the feature scope. It is used for cleanup in FeatureDeactivating
// Next, we can provision the same custom action again and again to different
// locations. For example, let's register it for Links list:
Btw, Provision method has many overloads, in easiest case you should provide only 2-3 params.
You can find more samples at the project site.
P.S. Please, do not forget to add reference to RibbonUtils.dll & add record into GAC deployment list (Package.package, 'Advanced tab', Add -> Existing assembly)