I have a new Specialized Roubaix Elite with a carbon frame. The manual specifies a maximum torque of 55 in-lbf for the seat post collar. Is there an allen torque wrench to help me with this?

There are allen sockets with 3/8" drive to fit any ratchet or torque wrench

Since the spec is in in.lb you will need an in.lb torque wrench to measure that small amount. They make a 3/8" drive in.lb torque wrench, though the 1/4" drive in.lb torque wrench is much more common.

Then you will need the corresponding allen head drive sockets. This set contains both 1/4" and 3/8" drive sockets so you will need either this adaptor or that adaptor to mate some of the sockets to whatever size torque wrench you choose.

I bought a set of Allen wrench sockets that fit my regular torque wrench.

Which is fine if your regular torque wrench will measure 55 in.lb (less than 5 ft.lbs) accurately.

The1/4" drive hex metric sets are EXPENSIVE unless you know where to find them. I got a 1/4" torque wrench (20 in-lb)from local discount tool store for about $20 but the 1/4" hex metric sockets are harder to find. On regular eBay, they can also be rather expensive but if you go to the eBay Motors you can find the 1/4" hex sets a lot cheaper. I got a metric set that included 1/4" drive with 2-6mm for $20.
Another option is to use the 3/8 size sockets with a reducer to the 1/4 drive. You will want a 1/4" torque wrench. The 3/8" size generally do not go to the lower torque values.

I purchased my 3/8 drive metric set at Sears (Craftsman).....don't remember the price.

You can easily get a 3/8" Male to 1/4" Female stepdown adapter that will let you use any 3/8" drive socket on a 1/4" drive ratchet or torque wrench. Any hardware store, Sears or Home Depot/Lowes has them.

Making your own Alen bit sockets is easy if you have a Dremel tool with a cut-off wheel. But a set of L-type Allen wrenches and cut off a 1" or so piece from the long arm using the Dremel. BTW, you cannnot cut even cheap Allen wrenches with a hacksaw so don't even try.

Use the straight sections in regular metric sockets as needed. If you want to make the bits more permanant, superglue or epoxy the Allen sections into a cheap set of sockets.

Craftsman has a torque wrench that goes from 20 to 250 inch-lb in 3/8" drive. About $70 or so at K-Mart.

The Allen bits that I have for it are also Craftsman, and are ok except that they're chamfered slightly (which makes it easier to get them engaged properly in the bolt) but which removes some mating space once you have it in there. This isn't so good on bikes since a lot of the bolt heads aren't that deep, and the torque wrench is fairly large and unwieldy itself - you have to use care to keep the tool from popping off the fastener. So I'm keeping my eyes open for some that are more squared off and with a lower profile overall.

The technique Hillrider mentioned above is pretty clever and intriguing to me and I think I might give it a shot. Sooner or later everyone gets some worn out allen wrenches and sockets, and this would be a way of turning two bits of trash into something useful.