The latest SDK can be downloaded from here: http://software-dl.ti.com/sitara_linux/esd/AM35xSDK/latest/index_FDS.html
Here is the Sitara Linux Software Developer's guide and here are the SDK Installer Execution Steps. Install it in your virtual machine and try using the create-sdcard.sh script located inside <sdk_dir>/bin/ to create a new sd card using the prebuilt images.
Best regards,
Miroslav