You are using Debian, right? You're in luck, I just managed to get sending and receiving of Yahoo webcam using Gyach's new update working.
To install, make sure you have alien installed first. If not, then open a terminal and as root type:
apt-get install alien
Click on the .rpm link below and select a mirror, then save the file on your system. Open a terminal and navigate to it, then type as root:
alien -d Gyach-Enhanced-pYVoiceChat-1.0.7-1.i586.rpm
This will create a .deb file which you can then install using your favorite package manager, or, if you wish to install it right away in one go, then type as root:
alien -d -i Gyach-Enhanced-pYVoiceChat-1.0.7-1.i586.rpm
To start Gyach, type in the terminal (as user):
Make sure when you see the log in screen that you put a check next to "No chat room", unless you want those of course.