The product is called Cisco Services for IPS. It provides signature updates, hardware support for the IPS module itself and TAC access: -
http://www.cisco.com/en/US/services/ps2827/ps6076/services_qa0900aecd8022e962.pdf
You need an existing service contract on the firewall platform too, but guess the 5585-X already has that.
I didn't think you could enter SMARTnet products into CCW, but could be wrong.
I know some distributors use their own part numbers for SMARTnet services, making it harder to tell them what you need in the form of a single part code.
A cheaper option to Cisco's direct SMARTnet offerings is to use 'Shared Support' via a gold partner. Make sure the gold partner only works with other Cisco channel partners and doesn't have their own customer base. You don't want your customer details leaking over to the dark side of their business.
Personally, I would not use the Shared Support model for a firewall of this size. With SMARTnet, Cisco will keep a nice shiney new one in the local depot ready to ship to site. In my experience, replacement kit through Shared Support cover is generally second user, often a bit battered and very occassionally faulty. I dont' know for sure, but doubt very much they assign a dedicated device per contract. It's likely to be a contended pool of kit. You get what you pay for to some extent, although the price difference between this and SMARTnet is often very large.
There is a third option called Cisco Smart Care. I don't know much about this, but I think the partner has to front the support calls. You also allow Cisco remote monitoring of the customer kit. I think this all forms part of their SIO, so they get something from it. It's cheaper than SMARTnet. No idea what IPS offerings there are with this.
Sorry if I went on a bit!
