This is just something I picked up over the weekend to interface with Terminal.app via AppleScript:
NSString *s = [NSString stringWithFormat:@"tell application \"Terminal\" to do script \"cd %@\"", folderPath];
NSAppleScript *as = [[NSAppleScript alloc] initWithSource: s];
[as executeAndReturnError:nil];
The intent is pretty easy to pick up (Also, please feel free to handle the error). The question and answer can be found on StackoverFlow.