Damn FAT32 is keeping me from transferring 4.5GB files from my PC to my N9. Does anybody know how I can bypass this limitation?

You can't, that's a limitation of the file system. Only way is to split the files up so that the files are less than 4GB.

You can format the filesystem as ext4 which will bypass the limitation, only drawback is that you need to use scp to transfer files after that as mass storage mode stops working.

Does that mean that mass storage mode with ext4 ~/MyDocs partition doesn't work even when connected to a Linux system? Using SSHFS for mounting ~/MyDocs probably makes file operations slower, but I don't really use mass storage mode at all as SSH is simply more convenient (no fiddling with usb cable needed). Just asking out of curiosity.

Of course it works, I think rainisto meant his advice for people using windows hosts.

Another way to do the transfer, is to boot the device with a rescue kernel (or rescue mode in ubiboot if you use that) and then just copy the file to the exported partition.

I wonder though where the original poster would want to upload that large file to, if the MyDocs is formatted as FAT... As far as I know that's the only partition sized large enough to hold anything like that.
(unless there's been some partition resizing going on...)

Well its' movie file actually.

i was wondering how to format the partion to ext4?

also is this limitation of mass storage mode to FAT only for windows hosts?
could I choose mass storage mode (if the partion was formated with ext4) and mount it on a linux/mac/unix/ host using the usb cable?

There was a guide somewhere on TMO how to do it.
Just unmount it and use "/sbin/mkfs.ext4"
You need to change the fstab entry and the mounter script.

After that everything works just like before except it's not usable in windows any longer, linux use is just as before.