How does one export a PDB structure to SVG?
If you haven't found answer till now, you can use VESTA (Visualization for Electronic and STructural Analysis) package. It is a freeware and can be downloaded from 
http://jp-minerals.org/vesta/en/

It is available for both Windows and Linux. It can be used to import any many structural files (pdb included) and get an output in any supported format(which includes SVG). From their website:


  VESTA is a 3D visualization program for structural models, volumetric data such as electron/nuclear densities, and crystal morphologies.


However, if you do not strictly require SVG format them my personal favorite is "QuteMol". It gives way too many options to adjust visual representation
It is an open source (citeware, i.e. you have to cite their paper for any academic publishing) molecular rendering software available from:

http://qutemol.sourceforge.net/ 

It can generate PNG, JPEG anf GIF(animated) images of maximum dimensions up to 8192x8192 pixels so you can use them for high resolution printing/posters etc. too. One small flaw is that it is rather ill maintained and considerable amount of bugs are there.For e.g. using default options is fine but in case you want to use customized colour scheme then their example ART(atomic rendering table, just a table of atomic symbols, their radii, and colour in RGB codes) file gives following example:


  X    0       0.853  204    0    0
  
  H    1    0.930  199  199  199
  
  He    2  1.085  107  115  140
  
  Li    3  3.100    0  128  128


However in reality you will require 2 colums of radii for programme to recognize it (core and vander waal radii). Similarly atomic symbols with single alphabet are not rendered properly!!! But all these problems have work around and results are worth it (specially for large protein molecules).
sample this:

(source: sourceforge.net)