Install AIDE from Google Play on your Android device (all Android versions from 2.2 are supported) and start it.
AIDE uses the Eclipse project format, so any Eclipse Android app project can be opened in AIDE. This makes it easy to switch between the tools. To open an Eclipse project on your device with AIDE, first copy the source files to the SD card - either manualy, or using Dropbox, or using Git. Then open AIDE's built-in file browser and go to the directory that contains the source files. AIDE will recognize the Android project and offer an option "Open this App Project".