Sorry to bump this 4-month old thread, but I’ve done some actual research on the topic and I’ve gotten somewhere with the problem.
From what I’ve read, 9x itself only support SSL 2.0 (and maybe 3.0), and if you don’t have 98 SE or IE 5.5 installed, then it won’t support anything else. If IE 5.5 is installed, then when TLS support is enabled, connecting to Escargot’s web services will still backfire since the oldest TLS cipher suite Escargot supports is TLS_RSA_WITH_3DES_EDE_CBC_SHA, and 9x doesn’t support RSA. If I can find any suitable TLS cipher suites for 9x (and XP installs with IE < 8), I’d be glad to bring them up here.
Even though it may seem that I’m regurgitating old info with minor details sprinkled in, here’s where the new discovery comes in (at least in public). Escargot doesn’t have any kind of SSL support, which means that non-TLS compatible installs of 9x won’t be able to connect to Escargot’s web services at all. Although SSL is prone to vulnerabilities nowadays, I feel that Escargot should aim to be compatible with as many legacy systems as possible, since these are old applications we’re dealing with that are expected to work on these old systems. It’s especially important considering the upcoming Yahoo! Messenger frontend utilizes web frontends for some of Yahoo!'s features, one being creating and deleting aliases, and having those features inaccessible on one of its target systems wouldn’t make much sense. If I had more expertise and time to dig into what cipher suites 9x and XP support, then I’d be able to pitch a possible solution to @valtron. 