If you are adventurous, here the process to have Hipchat working in your favourite IRC client:
First, you need to install the IRSSI XMPP plugin. You can find this package in your distribution, but I advice you to use the latest version possible if you don't want this segfault errors everywhere: http://gna.org/bugs/?20487
The first version released after the patch fix is the 0.52-2 that you can download here: https://launchpad.net/ubuntu/+archive/primary/+files/irssi-plugin-xmpp_0.52-2_amd64.deb (No dependencies so it should work in any Debian distributions)
Once it's done. You have to configure IRSSI. Either via command line, either manually in the ~/.irssi/config file. I followed this thread: http://cybione.org/lists/irssi-xmpp-list/msg00339.html and it was pretty successful.
You can find your XMPP access on your HipChat account on this page: https://boxuk.hipchat.com/account/xmpp. Everything has a XMPP account id. Even the Rooms name. So you have to use these instead of the real names for your IRSSI config.
One last thing is that HipChat don't let you choose the nickname you want. Your IRSSI one must be the same as configured in HipChat.
To make it work nicely alongside my current IRC config, I configured the alternate nickname.
Finally, once all that is done.
Load the XMPP plugin
Change your alternate nickname
/set alternate_nick Your Full Name
And connect to HipChat
If you want to manually join a channel
Also, to have a private discussion with someone, you can use the Full Name
/query "Aurélien Thieriot"