Daily built packages
Bitlbee offers daily builds for debian like linux distros. They are located at:
http://code.bitlbee.org/debian/
Since these are binary packages they may not be usable for you if you're using a less common platform. Right now, 32-/64-bit Intel and ARM platforms are supported.
An up to date list of available distros and architectures is available in the repo readme at:
http://code.bitlbee.org/debian/README.html
The most common way of adding the BitlBee repository, is by adding it to your sources.list file, located at /etc/apt/sources.list. Alternatively you may create a new file /etc/apt/sources.list.d/bitlbee.list.
The line you need to add might look something like this for a 32-bits system:
deb http://code.bitlbee.org/debian/master/jessie/i386/ ./
And for a 64-bit version:
deb http://code.bitlbee.org/debian/master/jessie/amd64/ ./
Or if you're using an ARM-based machine:
deb http://code.bitlbee.org/debian/master/jessie/armhf/ ./
The master subdirectory means that it is the main development branch of bitlbee. The jessie subdirectory means that it is intended for the Jessie (8.0) release of Debian and the i386 subdirectory means that it is intended for an i386 (32 bit) version of the operating system. You can check if you need 32 or 64-bits using the uname -m command.
After adding the repository and the GPG key (optional, see below) do sudo apt-get update and then install with sudo apt-get install bitlbee (aptitude may be used instead of apt-get).
For the GPG key, copy-paste the following into your terminal
wget -O- https://code.bitlbee.org/debian/release.key | sudo apt-key add -