How do I send an HDF dataset to a ClearSilver template?

I've been modifying a trac module, and it uses the ClearSilver template language. I need to get a list of strings to the template to load into a select control. The problem I'm running into is that it is not at all clear to me how I would expose data to the template. I'm using trac 0.11.3 on apache2 with mod_python, could someone help me with this? I feel like I'm missing something really easy.