Eagle CAD Thermal Vias
Just add normal vias using the via command. As you said:


  They are just normal vias placed under the thermal pad


The drill size may become important if you are going to production, since the vias will suck some of the solder. 
Also it may be a good idea to keep the other side of the PCB without solder-mask if you are going to hand-solder this board.

Rant: It's possible to write a ULP program to create a via matrix, but since nobody needs so much vias it doesn't exist.