This is for future reference for me – for some reason this is a huge pain in the ass for me to find whenever I need it.
Here is the official documentation on how to integrate BC3 with TortoiseSVN.
Here are my settings (on 64 bit machine):
"C:\Program Files (x86)\Beyond Compare 3\BComp.exe" %base %mine /title1=%bname /title2=%yname /leftreadonly
Put the SAME THING for both "comparing different revisions of files" and "comparing different revisions of properties".
"C:\Program Files (x86)\Beyond Compare 3\BComp.exe" %mine %theirs %base %merged /title1=%yname /title2=%tname /title3=%bname /title4=%mname