XML as Input to Kettle Transformation

Dear All,
I am a beginner in Pentaho DI (Kettle & Spoon). My requirement is to segregate the CDR's produced by MSC(in ASN BER Format) for a telecom operator ( as HOME users/ROAM users). The segregated files (should be encoded back to ASN BER) would be used by Billing Systems (Hence I want the same input record to be available at the last step).

There is a decoder process which decodes the ASN files and generates an XML(can't use CSV's because of the tree structure of the fileds).
The XML's parent tag is <CallDataRecord>, and can have either <pCSPLMNCallDataRecord>(single CDR) or <compositeCallDataRecord> (multiple CDRs)as its child elements.
<compositeCallDataRecord> will inturn have <pCSPLMNCallDataRecord> as its child node.

So I have to read the XML, and if its single CDR then I have to check for say MSOriginating/MSTerminating..etc..and if its a composite CDR, i need to loop through that many number of times (processing as single CDR).

I have a tight deadline for the delivery. Any help would be appreciated guys.

Thanks a LOT,
Ujjawal Rathor