Hmm, I've bit of a problem, I need to fetch a string from an attribute in an
xml-file and then see if there's a parameter with the same name (parameter
to the stylesheet that is). Can't find any way to run filters on parameters
like I can on elements, anyone know how to accomplish this?

You can see whether a parameter with the same name exists:
  document('')/*/xsl:param[@name=$attribute-name]
but I'm not aware of a way to get the value assigned to the
parameter. XSLT has been designed to be a compiled language.