Can a jsonp ajax call be done with xml?

Can a jsonp ajax call be done with xml?

Hello,

Im trying to do a mapquest cross-domain ajax call. 

But, the format of json they want is not valid. They are expecting the json to be formatted as such:
json={locations:[{street:"York,PA"},{street:"Red Lion"},{street:"19036"},{street:"300 Granite Run Dr, Lancaster, PA"}],options:{thumbMaps:false,maxResults:1}}


But this format is not valid in jquery. It even fails in the json validator website. Thusly, Im getting errors all over the place. It must have double quotes for "locations" and "street" among other places. If I try to send it in the correct format, it fails on their end.

They have an xml type that I can send, but this is a cross-domain call and Im not sure if or how I can send xml cross-domain using jsonp.

Any suggestions?

Thanx in advance.