How to manage bandwidth on router?

[Stalvros]

Hi there, I'm not sure if this belongs in THIS section,
but do let me know if I posted at the wrong page.

Basically, I wanted to ask more about bandwidth management.
I've got this router at the moment;
http://reviews.cnet.com/routers/asus-rt-n66u-dark/4505-3319_7-35110985.html

I'm only talking about the WIRED part.
So basically, it has 1 port in (for the modem)
and 4 ports out (to all the pcs that'll be using a wired connection).

I've got a total of 4Mbps download and a 0.4Mbps upload.
How do I set it to custom?

Like for example;
Port Out A can only download a max of 1.75Mbps and 0.175Mbps upload.
Port Out B can only download a max of 0.5Mbps and 0.05Mbps upload.
Port Out C can only download a max of 1.5Mbps and 0.15Mbps upload.
Port Out D can only download a max of 0.25Mbps and 0.025Mbps upload.

Or, forget about the upload.
The upload can be shared but NOT the download.
Is it possible?

I went to the software management of the router itself
but it didn't give me such configuration option.