You fill in the mfr. recommended pattern in the "Footprint Tab"

 

 

 

And this land pattern is "over the top" detailed.

 

 

You can create a good Footprint using the "Molded Body" component family and then select the "Footprint" tab to enter the mfr. pad sizes and spacing.

 

I think the center pad "wings" are for the alternate part.

 

Here's a link to the T528 Low ESL. Facedown Tantalum Polymer Capacitors.

The terminal dimensions are on page 4.  The pad dimensions on page 7 are for the W and Z case, to allow a low ESL connection to the PCB and to allow connection to competitor's three-terminal device. The competitor created a three-terminal device, but there are two cathode connections.  The cathode connection is broken into two to eliminate huge disparities in solder pod areas that could cause the larger cathode plate to lift chip and break anode pad connection.  On our 7343 device we have only two terminals, anode and larger cathode, but recommend using two solder pads for the cathode to eliminate the propensity to lift.  We do not believe that three solder pads are necessary for the smaller case devices.

 

Our programmers need to see what your request is. They don't want to assume anything.

 

Aside that, the new "Package Designer" will be released this weekend in V2013 and you can create many non-standard library parts. You can even import ASCII files with X,Y coordinates and pin names for padstack placement.

 

We need the land patterns to be non-symmetrical for a polar capacitor.  

Cathode plate is larger to allow greater heat dissipation, and polar mounting.