Here is a Gujarati Unicode Keyboard. It is almost phonetic. I have made some changes to increase the speed of typing. I have uploaded this file as doc, please rename it after downloading it as .zip file first and then unzip the folder and install it. I will post other article for instruction how to use it.
Please save this file in to your computer. If you try to open it, it cannot be opened, just save. Then rename this file with file extension .zip that is change the file extension from .doc to .zip. And then unzip it. You can then click on the executable file to instal the keyboard.