You have to enable the install of unsigned application in the settings:
Settings -> Application -> Unknown sources (Allow installation of non-Market applications)
So you need to send him the file by mail or what ever and he needs to make the settings modification and install the file.
There is no need to sign the app in order to install it on a phone. if you ever ran this app in the emulator and .apk file will automatically created in the \bin folder of you project folder. just copy this file/ send it by mail for him to install.
