We are using SDL Tridion 2011 SP1 to build an application .NET MVC 4. Each page that is published corresponds to a view. It was rejected for technical reasons to use DD4T. Could we still use the User Interface update for SDL Tridion 2011 SP1 (aka. UI 2012 or next version of SiteEdit or previous release of Experience Manager aka. XPM) in the system we have?
User Interface update for SDL Tridion 2011 SP1 (also known as UI 2012) is working on top of your website, so whether you are using an MVC web application, ASP.NET webforms or plain old static HTML pages doesn't really matter.
All you need to make sure is that the correct markup is written out for each Page, Component Presentation and Field you want inline editable.
Depending on how you publish the content to your .NET MVC 4 application, you might still be able to use the Enable (Inline) Editing Template Building Blocks from SDL Tridion to generate this markup, or you might need to generate it yourself as is done in DD4T.