You should be able to do this with xmlstarlet and a little scripting. I don't have a good xml file to run this against but this should do it, more or less. Should output all matching elements to tempfile.txt and then splits out the elements into output1.xml and counts up until all elements have been saved into their own xml files.
sourceFile=$1
xmlstarlet sel -t -c "/your/element" $sourceFile -n -o "splithere" > tempfile.txt
fileNumber=0
cat tempfile.txt | while read line; do
if [[ $line == splithere ]]
then
let fileNumber++
break
fi
echo $line >> output$fileNumber.xml
done
rm -f tempfile.txt
You should be able to do this with xmlstarlet and a little scripting. I don't have a good xml file to run this against but this should do it, more or less. Should output all matching elements to tempfile.txt and then splits out the elements into output1.xml and counts up until all elements have been saved into their own xml files.