The sources for 3.0x are online now, so you do not need a license to get
those... just ftp to cu-seeme.cornell.edu.
If you obtain an internal use only license, you can obtain the 4.0 source
code, however at the current time the version that they have online is
still 4.0b2, not 4.0b3. Perhaps the changes that took place between these
versions are not that significant, but I was still disappointed to find
this out. I've emailed the Cornell folks, hopefully they'll place the
current versions online in the short future.
- Chris