Well, I think your best bet is to read the fstab and then surf the web for solutions or post it here and see if anyone could help. From my point of view and from personal experience, I suggest you to try appending umask=000 or rw at the beginning of the 3rd column of the entry you are supposed to modify.
It may look like this
/dev/hdb1 /home/foo vfat umask=000,auto,user 0 0
/dev/hdb1 /home/foo vfat rw,auto,user 0 0
The umask argument is used to "mask" the file permissions of the files and directories under that directory (at least is what I have understood so far). You may learn a lot if you search for this over the internet. What I have learned is that the argument passed is the complement (in octal) of the desired permission you want in that partition, ie: if you want it to be 777 you use 000.
I used the solution above, it worked at the first try. In the "rw" case (which I haven't tried yet) I am not sure if the permissions of the existent files are preserved, anyway, it's your choice.
Check this out and see what you can get:
Or read de man for fstab and mound if you wish...