I have extended the "US International" Windows keyboard so that you can type macrons without much effort. Please download the keyboard from http://www.learnlangs.com/usIntExt.zip
and run the setup. After that, you should have the option of switching to a "Maori" keyboard instead of the usual English one. While that keyboard is activated, you can type macrons by first typing a dash - and then the vowel (lower- or uppercase) that you need. You can also type Esperanto chapelliteroj by using the ^ key and then C, G, H, J, S or W (for U). And of course you still have the ability to type French, Italian, Spanish, Portuguese and German diacritics, as with the regular US International keyboard. Only disadvantage is that if you want to type a dash, you will either have to use the minus key or dash key plus space. I hope somebody will find this helpful!