From the HDFS explorer, you should be able to select the windows event log sourcetypes from the pulldown in the uncategorized section - try using the filter box to type in your sourcetype.
There's more documentation on how props and transforms work in here: http://docs.splunk.com/Documentation/Splunk/6.2.5/Knowledge/Createandmaintainsearch-timefieldextractionsthroughconfigurationfiles
But generally, props.conf contains stanzas where the stanza name can be a number of things, including source:: and . So if you want to associate a source with an existing sourcetype, you can add a stanza for your new source. ex.
[source::...mylogsalllooklikethis.log.*]
sourcetype = WinEventLog:Application
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