The Brock source code can be retreived from the CVS archive at enhydra.org.
Using either a user created for you ( committers of Brock or other enhydra.org projects) or the anonymous access. The procedure for getting sources out of the CVS tree at enhydra.org can be found on the enhydra.org site here :
For those of you who don't have or know how to use CVS (which is rather simple by the if the basic instructions are carefully followed), you can get a zip file with all the source tree in it. This is not necessarily synchronized with the CVS tree and it may hold experimental code since this is taken out directly from the dev. machine I use. So here you are : Brock sources zipped (BrockSrc.zip).