Hop,

I'll answer my own question.

Basically, I created a document type called "Reusable content" with just a " ReusableContentBody" property. Then I created a macro with a content picker parameter and the view is the following:

@inherits Umbraco.Web.Macros.PartialViewMacroPage

@using SFPD.Core.DocumentTypes;

@{
    if (Model.MacroParameters["ReusableContentRef"] != null)
    {
        var item = Umbraco.TypedContent(Model.MacroParameters["ReusableContentRef"].ToString());

        if (item.DocumentTypeAlias == ReusableContent.ModelTypeAlias)
        {
            var rc = item as ReusableContent;

            <div>@rc.ReusableContentBody</div>
        }
    }
}

So I just retrieve a reference to the parameter value, I checked if the document type is correct, and if it is, I display the property and poof, I have reusable contents.