Most probably, the project files for MSVC 6.0 are not updated, since really few people uses MSVC 6.0 and CS is trying to support MSVC 6.0 as little as possible.
You have to modify manually the project files, maybe if you join #crystalspace on irc.freenode.net you will have more chances to get help on how to fix the project files.
Another good solution is to abandon the use of MSVC 6.0 - you will anyway get other kind of troubles compiling CS-CEL or PS and use or MSVC 7.x, if you can, or MinGW.
