If you just want to download the pdf then wouldn't a simple link work:
Code:
<a href="http://win2012svr:8080/ReportServer?%2fxreport%2fcodedetailed&D1=2012-09-01&D2=2012-09-30&RATE=PUBLIC&rs:Command=Render&rs:Format=PDF">Download</a>
This requires clicking, of course, but I suppose something like a hidden iframe might be used to trigger the download..?