So, you are asking how to get read/write access to NTFS partitions from MacOS (not just how to access your Boot Camp "installations" from MacOS)?
You need to install an NTFS file system driver. I personally use the Paragon NTFS driver for MacOS, and it works great. In the past I have used a free one, and it worked OK, but it was slower at some things. I even recall reading posts somewhere on changes to your FSTAB to get Leopard (and possibly Snow Leopard) to give you read/write access, but I haven't had a need for those to see if they work or not.