There seem to be interest in Amazon MWS and because mostly their customer service is awe-full as well as the documentation, it's a real challenge when it comes to implement it.
First things you are going to need when dealing with MWS is signature generation. Bellow are the functions i use for it:
<cffunction name="HMAC_SHA256" returntype="binary" access="public" output="false">

<cfargument name="signMessage" type="string" required="true">

<cfset var jMsg = JavaCast("string", arguments.signMessage).getBytes("UTF-8")>

<cfset var jKey = JavaCast("string", this.theSecretAccessKey).getBytes("UTF-8")>

<cfset var key = createObject("java", "javax.crypto.spec.SecretKeySpec")>

<cfset var mac = createObject("java", "javax.crypto.Mac")/>

<cfset key = key.init(jKey, "HmacSHA256")>

<cfset mac = mac.getInstance(key.getAlgorithm())>

<cfset mac.init(key)>

<cfset mac.update(jMsg)>

<cfreturn mac.doFinal()>

</cffunction>

<cffunction name="GenerateSignedAmazonURL" returnType="string" output="yes">

<cfargument name="HTTPVerb" required="yes">

<cfargument name="HostHeader" type="string" required="yes">

<cfargument name="HTTPRequestURI" type="string" required="yes">

<cfargument name="RawQueryString" type="string" required="yes">

<cfset var signature = "">

<cfset var encodedQueryString = "">

<cfset var sortedQueryString = "">

<cfset var encodedSignature = "">

<cfset var name = "">

<cfset var value = "">

<cfset var i = "">

<!--- get your timestamp--->

<cfset var thenow = DateConvert("local2Utc", Now())>

<cfset var time_stamp = "#DateFormat(thenow,'yyyy-mm-dd')#T#TimeFormat(thenow,'HH:mm:ss')#.00Z">

<!--- append timestamp to query string --->

<cfset arguments.RawQueryString = arguments.RawQueryString & "&Marketplace=#this.marketplaceID#">

<cfset arguments.RawQueryString = arguments.RawQueryString & "&Merchant=#this.merchantID#">

<cfset arguments.RawQueryString = arguments.RawQueryString & "&SignatureMethod=HmacSHA256">

<cfset arguments.RawQueryString = arguments.RawQueryString & "&SignatureVersion=2">

<cfset arguments.RawQueryString = arguments.RawQueryString & "&Timestamp=#time_stamp#">

<cfset arguments.RawQueryString = arguments.RawQueryString & "&Version=2009-01-01">

<!--- start building signature --->

<cfset signature = arguments.HTTPVerb & Chr(10)>

<cfset signature = signature & LCase(arguments.HostHeader) & Chr(10)>

<cfset signature = signature & arguments.HTTPRequestURI & Chr(10)>

<!--- loop over the list and urlEncode each value --->

<cfloop list="#arguments.RawQuerySTring#" delimiters="&" index="i">

<cfset name = ListGetAt(i, 1, "=")>

<cfset value = "">

<!--- if this item has a value encode it --->

<cfif ListLen(i, "=") gt 1>

<cfset value = Replace(Replace(Replace(ListGetAt(i, 2, "="), ",", "%2C", "ALL"), ":", "%3A", "ALL"), " ", "%20", "ALL")>

</cfif>

<!--- build the new query string with encoded values --->

<cfset encodedQueryString = ListAppend(encodedQueryString, "#name#=#value#", "&")>

</cfloop>

<!--- next we need to canonically order the queryString params --->

<cfset sortedQueryString = ListSort(encodedQueryString, "textnocase", "asc", "&")>

<!--- append to the signature --->

<cfset signature = signature & "AWSAccessKeyId=#this.accessKeyId#&" & sortedQueryString>

<!--- encode the signature --->

<cfset encodedSignature = URLEncodedFormat(ToBase64(HMAC_SHA256(signature)))/>

<cfreturn "https://#arguments.HostHeader##arguments.HTTPRequestURI#?AWSAccessKeyId=#this.accessKeyId#&#sortedQueryString#&Signature=#encodedSignature#">

</cffunction>

The original version of GenerateSignedAmazonURLi found somewhere time ago when working with AWS and i think i slightly changed it.
The call would be like this:
<cfset generatedURL = GenerateSignedAmazonURL('POST', 'mws.amazonservices.com', '/', signStr2)>
A thing to note:POSTin generatedURL should go with POSTtype CFHTTPsand use GETin generatedURL for GETtype CFHTTPs.