Licensing is managed by the server. The client adjusts its capabilities based on what the server tells it. So as long as your server has its license keys properly configured, your Mac OS X client should be fine.

PS - There is a tech note under development that covers Team Concert on Mac OS X. You may wish to subscribe to the work item:
https://jazz.net/jazz/web/projects/Jazz%20Project#action=com.ibm.team.workitem.viewWorkItem&id=58194

Bill Higgins
Jazz Web UI Foundation Team

Is it necessary to have a license for the RTC 1.0 OS X client to connect? If so, how does one apply the license jar from XL without the license manager present or is there another route?

A draft is ready, but you may need to access the source (SCM) to get at it. There's no document link that I can find, which seems like an odd place to put documentation for review.

In any event, I hope when this is finalized it is simply posted to the technote section of jazz.net.

I've reviewed the document and figured I'd share the details in it here to get folks going. I'm sure it will be approved soon for general use.

Installs:
(1) OSX client in incubators works as-is
(2) Download the linux server .zip and unzip in a known location, <server>.
(3) Download the build engine .zip and unzin in a known location, <build>

Changes to make:
(1) <server>/server/server.startup
(a) Change JRE_HOME to /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home
(b) Add the following parameter to JAVA_OPTS: -XX:MaxPermSize=256m

(2) <server>/server/server.shutdown
(a) Change JRE_HOME to /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home

(3) <server>/server/tomcat/conf/server.xml
(a) Change IbmX509 to SunX509

How to run:
(1) Start Server
sudo <server>/server/server.startup
(2) Stop Server
sudo <server>/server/server.shutdown
(3) Run Jazz Build Engine
-- Navigate to <build>/buildsystem/buildengine/eclipse
-- Run the following:
java -jar plugins/org.eclipse.equinox.launcher_*.jar -repository https://localhost:9443/jazz/ -userId <user> -pass <pw> -engineId junit -sleeptime 5

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For the record, Andr Weinand has been working on this note so all credit goes to him for writing this up. You can see the work item for some work on launchd configs Patrick Mueller is working on.