and you'll have to 'fix it' each time a Unity update 'broke it'). Not sure if this works in Parallels, but in VMWare, it does: You can open Windows-applications directly from Mac OS so you need to create a build of a modified version of what's posted in that thread and create a symlink from Unitron to that application (yeah, you do replace Unitron that way. This hack is based on the solution provided in Windows version: integrate with Visual C# (which is redundant for Windows since Unity 2.6 but still very relevant for the Mac OS version of Unity). There's also a 'hack' to make Visual Studio open the file you clicked on in the virtual machine, in Visual Studio (including opening the correct solution file generated by the Unity-Visual Studio integration). see also the Setting up Visual Studio for Unity (that article was from before there was Unity for Windows, so while it's a little dated in parts it deals with a lot of the issues involved in setting this up in a virtual machine).
Personally, I really think the only 'alternative' to Visual Studio on the Mac is.