Howto use update-initramfs

Hi all,
 I've been trying to manually update the initramfs . One command which I came to know is

sudo update-initramfs -u ALL

but this only updates the initramfs for the current kernel .

what about if I want the the initramfs to be updated for all kernels ?

I tried doing this :-

shirish@Mugglewille:~$ sudo update-initramfs all
[sudo] password for shirish:
You must specify at least one of -c, -u, or -d.

Usage: /usr/sbin/update-initramfs [OPTION]...

Options:
 -k [version] Specify kernel version or 'all'
 -c Create a new initramfs
 -u Update an existing initramfs
 -d Remove an existing initramfs
 -t Take over a custom initramfs with this one
 -b Set alternate boot directory
 -v Be verbose
 -h This message

Then doing this :-

shirish@Mugglewille:~$ sudo update-initramfs -u all
update-initramfs: Generating /boot/initrd.img-2.6.24-12-generic

I have 2.6.24-11-generic as well & wanna update the initramfs for that kernel as well.

shirish@Mugglewille:~$ sudo update-initramfs -k 2.6.24-11-generic
You must specify at least one of -c, -u, or -d.

Usage: /usr/sbin/update-initramfs [OPTION]...

Options:
 -k [version] Specify kernel version or 'all'
 -c Create a new initramfs
 -u Update an existing initramfs
 -d Remove an existing initramfs
 -t Take over a custom initramfs with this one
 -b Set alternate boot directory
 -v Be verbose
 -h This message

Any ideas or clues as to how I can do this would be appreciatable .