You can use following code to convert string encoding using Java library:
<cfset oCharset = createObject("java","java.nio.charset.Charset") />
<cfset fromCharSet = oCharset.forName('utf-8') />
<cfset toCharSet = oCharset.forName('iso-8859-1') />
<cfset b = toCharSet.decode(fromCharSet.encode(q)).ToString() />
( read more on String encoding conversion )