I have found no definite way to detect IE6 using jquery.support
No, of course not — that's the whole point.
The dogma is that detecting support for particular features, and coding around the lack of them, is a better way of maintaining cross-browser compatibility than trying to keep track of every browser that exists and what it supports.
Whilst you could work backwards from jquery.support to guess what browser is running, and then use different code that relies on a completely different feature, that would be utterly perverse. You'd be taking the already-fragile approach of assuming browser ‘X’ supports feature ‘Y’, and making it even more fragile by adding another layer of unrelated feature sniffing that could pick up the wrong browser.
So the dogma answer is, don't ever detect IE6, or any other particular browser. Use a feature-sniffing solution such as jquery.support to see directly what features you can use, but don't assume that the presence or absence of feature ‘Y’ means you can or can't use a different feature ‘Z’ associated with the same browser ‘X’. Because that will always go wrong given a new or obscure browser/version you haven't met before.
And the dogma answer is, indeed, usually right. However in reality there are some browser bugs that can't be detected by feature-sniffing and need specific workarounds. And of course the one browser this almost always is, is IE6.
It is unclear whether you are in one of those situations as there is no detail in your question, but when you really do need a horrible hack for That One Browser, approximately the best solution is still conditional comments, dropped into JavaScript or HTML.