With the note you added to your first post, do you just want all quotes escaped? That doesn't need a regex, just search for " and replace with \" If you don't want the quote following the = to be escaped, but all others should be, we'd need to know more about what kind of regex your editor supports. I use UltraEdit and it had it own odd version of regular expressions that I had to learn to use, but in recent versions, unix-style support has been added, which I'm much more familliar with.
In perl, I'd use something like this:
Perl supports a variety of zero width assertions (don't know how many are standard supported), positive and negative, look-ahead and look-behind. This one uses negative look-behind. (?<!pattern) matches so long as pattern does not match what comes immediately before it, in this case, an equals sign. Since it's zero-width, it doesn't actually consume the character in the match, and there's no need for explicit back references.
Andrew - Perl (and VB.NET) Monkey
Never underestimate the bandwidth of a hatchback full of tapes.