Using AlphaVSS you can list the volumes using Alphaleonis.Filesystem.Volume.GetVolumes and GetVolumePathNamesForVolume
To emulate "vssadmin list shadows", generally it's like this:
Using y = CreateVssBackupComponents()
For Each z In y.QuerySnapshots()
'match z.OriginalVolumeName against the proper
' volume name matched in the GetVolumes command
'store the z.SnapshotDeviceObject string to use later
Using AlphaFS you can manipulate and open files on these volumes. I would simply list updated files based on a newer date stamp, but if you need byte-accuracy, you can open a data stream and compare the data within the .NET framework.
For high-speed data compare operations, you can use the following access to the Win32 API:
Declare Function IsArrayDifferent Lib "msvcrt.dll" Alias "memcmp" (ByVal byteArray1() As Byte, ByVal byteArray2() As Byte, ByVal bytesToCompare As Integer) As Boolean
Of course, it would be best if it was wrapped in a "safe" function to automatically determine the bytes to compare, and immediately return false if either array Is Nothing, or if the length of the arrays are different.