namespace DotNetNuke.UI.Skins.Controls
{
    public partial class TextPortal : SkinObjectBase
    {
        public string ShowText { get; set; }

        public string CssClass { get; set; }

        public string Source { get; set; }

        public string ResourceKey { get; set; }

        public bool ReplaceTokens { get; set; }

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
            string strText = ShowText;
            
            //load resources
            if (!String.IsNullOrEmpty(ResourceKey))
            {
                //localization
                string strFile = Path.GetFileName(Server.MapPath(PortalSettings.ActiveTab.SkinSrc));
                string strLocalization = "";
                strFile = PortalSettings.ActiveTab.SkinPath + Localization.LocalResourceDirectory + "/" + strFile;
                switch (Source)
                {
                    case "Global":
                        strLocalization = Localization.GetString(ResourceKey, Localization.GlobalResourceFile);
                        break;
                    case "Skin":
                        strLocalization = Localization.GetString(ResourceKey, strFile);
                        break;
                    default:
                        if (!String.IsNullOrEmpty(Source))
                        {
                            strFile = PortalSettings.ActiveTab.SkinPath + Localization.LocalResourceDirectory + "/" + Source;
                            strLocalization = Localization.GetString(ResourceKey, strFile);
                        }
                        break;

                }
                if (!String.IsNullOrEmpty(strLocalization))
                {
                    strText = strLocalization;
                }
                //strText = strFile;
            }
            
            //If no value is found then use the value set the the Text attribute
            if (string.IsNullOrEmpty(strText))
            {
                strText = ShowText;
            }
            
            //token replace
            if (ReplaceTokens)
            {
                var tr = new TokenReplace();
                tr.AccessingUser = PortalSettings.UserInfo;
                strText = tr.ReplaceEnvironmentTokens(strText);
            }
            lblText.Text = strText;
            if (!String.IsNullOrEmpty(CssClass))
            {
                lblText.CssClass = CssClass;
            }
        }
    }
}

And in the skin file I'm able to access the "SkinGlobals.resx" I created within the app_localresources for the skin by calling the SkinObject like this:

<dnn:TEXTPORTAL runat="server" id="dnnTEXTFooterPhone" CssClass=" " ShowText="" Source="SkinGlobals.resx" ResourceKey="FooterPhone" />

In addition, I've added the ability to also use the global resx for that portal as well by passing "Global" as the Source parameter.