Don't have the time to work it out entirely, but I think that HMAC SHA1 ColdFusion should be able to get you there. If for some reason you can't get it perfectly right (had that once) you might also consider using php-cli with cfexecute. It's not the fastest solution, but if necessary it allows you to use the php functions.
Edit: Copied the function from the previous answer and added a comment about the line that needed to be changed.
<cffunction name="hmacEncrypt" returntype="binary" access="public" output="false">
<cfargument name="signKey" type="string" required="true" />
<cfargument name="signMessage" type="string" required="true" />
<cfset var jMsg = JavaCast("string",arguments.signMessage).getBytes("iso-8859-1") />
<cfset var jKey = JavaCast("string",arguments.signKey).getBytes("iso-8859-1") />
<cfset var key = createObject("java","javax.crypto.spec.SecretKeySpec") />
<cfset var mac = createObject("java","javax.crypto.Mac") />
<!--- this line had to be changed to the 256 version --->
<cfset key = key.init(jKey,"hmacSHA256") />
<cfset mac = mac.getInstance(key.getAlgorithm()) />
<cfset mac.init(key) />
<cfset mac.update(jMsg) />
<cfreturn mac.doFinal() />