You can hack around it (but like I said, it isn't very clean). I can't speak for AppEngine or the others but on Windows Azure, you're really committing to Windows but not Windows Azure. So in theory, anything that works on Windows should work on us (we don't run things in a sandbox as some people like to say though we do run you currently in a normal user account without admin privs).
One way to implement this would be wrap a Windows Azure service around whatever you want to do on a node/server and then deploy that service. For example, if you have a Windows server where you install a ASP.NET app or a PHP site by xcopying binaries, you could do the same thing by wrapping that into a web role and put that in a Windows Azure service.
By doing this, you do miss out on some of the advantages of the platform but it should make it fit into your model.
One way to implement this would be wrap a Windows Azure service around whatever you want to do on a node/server and then deploy that service. For example, if you have a Windows server where you install a ASP.NET app or a PHP site by xcopying binaries, you could do the same thing by wrapping that into a web role and put that in a Windows Azure service.
By doing this, you do miss out on some of the advantages of the platform but it should make it fit into your model.