Without further detail, the best I can tell you is to read the ASA Traffic Shaping documentation here:

http://www.cisco.com/en/US/docs/security/asa/asa82/configuration/guide/conns_qos.html#wp1074879

That will allow you to assign a CIR (committed-information rate), Burst rate, etc.

If you have a single 4mbps link, you won't be able to physically partition it into 2/1/1 on the ASA per-se, but you can use traffic shaping and QoS to carve out chunks of bandwidth for certain IP ranges.

Hope that helps. Please rate if this post was useful to you.

Cheers,

Tim