In order to use a SCC tool with teststand sequence files, it's possible to use SeqFileDifferApp.exe deliverd by NI in the <Teststand>\bin folder.
For TortoiseSVN the following settings can be used:
"C:\Program Files\National Instruments\TestStand 4.2\Bin\SequenceFileDiffer.exe" %base %mine
For later versions of (32-bit) TestStand, the following settings can be used for TortoiseSVN:
"C:\Program Files (x86)\National Instruments\shared\TestStand\FileDifferLauncher.exe" %base %mine