In one case we bought a module where some items could be localized, but some items couldn't because the developer (I won't name him) didn't implement it.
And they were some important items like the texts for 'next', 'previous' buttons etc. so we really had a need for localization.

What we did was add the following code to the page (ascx file) we needed the translation:

<script runat="server">
Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
 If not IsNothing(FindControl("lnkNext")) then
   lnkNext.text = "Volgende"
  end if
 If not IsNothing(FindControl("lnkPrevious")) then
   lnkPrevious.text = "Vorige"
  end if
 If not IsNothing(FindControl("lnkSubmit")) then
   lnkSubmit.text = "Verzenden" 
end if
End sub
</script>