When I used HASHBYTES my solution was to covert all columns to varbinary and concatenate them together into one value to pass to hashbytes. It's pretty easy to auto-generate the correct statements using information_schema. The downside for me was that the data must reside on the server prior to hash generation and that pesky 8000 byte limitation. I found doing it in SSIS to be more efficient and got around the 8000 byte limit. One interesting feature was that the .NET hash functions for MD5 and SHA-1 generated the same hashes as HASHBYTES for string/character data less than 8000 bytes when I tested. That could be potentially useful, although I didn't do exhaustive testing on it.

I also posted a Connect item requesting CHECKSUM-style syntax to generate HASHBYTES-style hashes a few months ago. I'll post a link when I get to a real computer.