Hi,
In Beta 1 there was no out-of-the-box way to create a Tile Package from an existing cached map service. However we hope to add an option to ArcGIS Server cached map services to allow users to request an extent to be delivered as a Tile Package (.TPK) file. I don't think that functionality will be available in beta 2 though.
In the mean time, your options are to either open the map on which your tiled map service was based and use the tile packaging functionality to create a new Tile Package. Or alternatively, if you already have a cache which you would like to use wholesale with the ArcGIS Runtime then you may be able to manually create a TPK. The Tile Package is effectively a compact cache zipped up (no additional compression) into a single file - it's designed to be as portable as possible for ease of deployment. Therefore you could try zipping up an existing compact cache folder - if you're using the 7-zip application, the archive format needs to be "zip" and compression level should be "Store" for no compression. The zip file extension should then be renamed to ".tpk". This would obviously be an unsupported workflow - but will hopefully save you some time in the interim.
Cheers
Mike