arxiv.org is actually quite restrictive to alternative theories. If you do not succeed, you can put it on vixra.org. And, Vladan, whereever it is published one cannot expect any reactions to alternative theories today.
If your alternative theory is viable, then send it to the appropriate scientific journal for peer review. The thing is, that science WILL accept new, even ground breaking ideas - the burden of proof is just on the new theory. So you have to show that it works in the first place, and that it explains the observations better than the existing theory. There will be opposition and criticism, but if you do the work, it will pay back. On the other hand, if you just submit a hunch, or don't use science to prove your stuff (e.g. just discuss the topic philosophically), then it will get turned down, for a good reason: you didn't present your case convincingly enough.