It has been brought to my attention, that it is still possible to add custom server IPs to Xfire, in order to quick launch games.
IveMESTAR of the Survival and Obliteration Group forum has written a tutorial for that.
I am linking the forum entry here for anyone who wants to check it out:
Survival-and-obliteration.com
Please contact me if the link stops working. I have made a screenshot and will upload it here if that happens.