This is my first post.
If someone is interested I've made some modifications, to make bullet more standard respectly other library.
1) renamed src folder to bullet
2) added bullet/ to any header (and source if needed) #include directive
3) some changes to all(~) cmakelist files, for propely installation
4) bypassed INSTALL_LIBS and INSTALL_EXTRA_LIB
5) installation work
6) applied change from issue 610 (http://code.google.com/p/bullet/issues/detail?id=610
The modified version is tested only on linux (please test on other platform)