Stefan suggested using net.sf. instead of net.sourceforge (less characters).
Can't use ant-contrib (due to the hyphen), could use either ant_contrib or antcontrib?
Could either then try to mimic the ant hierarchy and go taskdefs.whatever, or just drop the taskdefs since almost anything that we would be doing would be a task.
The cpp tasks could be cpptasks, cpp, or cc.
So the pattern of potential package names:
net. [sf | sourceforge] . [antcontrib | ant_contrib] [ .taskdefs ] [ .cpp | .cc | .cpptasks ]
If I count right, there are 24 combinations.  If you have a favorite or an alternative, speak up.