You can find some related questions here
http://answers.ros.org/question/11051...
and here
http://stackoverflow.com/questions/16...
Following their advice and ahendrix answer I did the following on my Mac and it worked
1) Downloaded https://github.com/ros/class_loader/b... to somewhere on your disk
2) Added the following lines to CMakeLists.txt of your project
set(Poco_DIR _path_)
# replace _path_ with a path to PocoConfig.cmake that you downloaded before
find_package(Poco REQUIRED COMPONENTS Foundation Net Netd XML XMLd)
# add other components here
catkin_package(DEPENDS Poco)
include_directories(${Poco_INCLUDE_DIRS})
target_link_libraries(node_name ${Poco_LIBRARIES})
#replace node_name with the name of your project/node
Maybe it might be a good idea to find out if what you'd like to do is handled by http://wiki.ros.org/pluginlib .