Not sure why you are having trouble. I just blew away all my local maven snapshot download and was able to access the snapshot jars.
Hosting our maven snapshot repo on S3 is a bit of a PITA, but they are browsable here.
I don't think it makes a difference, but you might want to add the snapshots enabaled option to the pom
The dependency as listed in my example app pom.xml that I just ran is
<name>Springframework Maven SNAPSHOT Repository</name>