Quite a long time since my last post.
I have connected to trabber. It is worth a try. Thanks to Óscar for developing it and sending an e-mail.
We (Francesc Sebastià and I) have developed a small program that allows a Windows user with the spanish keyboard to write polytonical greek. It is a nice tool that we hope we will be able to offer for free and open source (by now the Electra group is financing the development).