First of all, in tt_news's locallang.xml, change the "more" setting to:

<label index="more"><![CDATA[<!--]]></label>

Then, use this in tt_news TS:

temp.tt_news_more_button = Read More

plugin.tt_news.displayList.subheader_stdWrap.append = COA
plugin.tt_news.displayList.subheader_stdWrap.append {
    1 = TEXT
    1.data = register:newsMoreLink
    2 = IMAGE
    2 {
      wrap = -->|</a>
      file = GIFBUILDER
      file {
        XY = [3.w]+19,12
        backColor = #898989
        1 = IMAGE
        1 {
          file = fileadmin/templates/main/img/button/arrow-right-grey.png
          file.width = 10
          file.height = 12
          offset = 0,0
        }
        2 = IMAGE
        2 {
          file = fileadmin/templates/main/img/button/corner-right-grey.png
          file.width = 9
          file.height = 12
          offset = [3.w]+10,0
        }
        3 = TEXT
        3 {
          text < temp.tt_news_more_button
          offset = 0,9
          align = center
      #    fontFile = t3lib/fonts/test/arial.ttf
          fontFile = t3lib/fonts/visitor/visitor2.ttf
          fontSize = 13
          fontColor = white
      #    niceText = 1
        }
      }
    }
  }