It's a big big job. The POV parser built into POV was written over many years in an incremental fashion. Writing a parser all in one go for the language as it currently stands is a mammoth job.
Excerpt from an old usened post  
The Nathan O'Brien's IRTC entry winner 'Glory'The complexity, flexibility and lack of formal specification of POV-Ray scene description language (SDL) have been pointed over and over as the main reason why POV-Ray modelers don't support POV-Ray SDL import. But none of the reasons listed above represents an impossibility, they only suggest the difficulties involved in a task that no one could honestly expect to be simple.
POV-Ray SDL import capability is something that users always wished for a modeler. It has been part of Bishop3D project requisites since day one and, in many aspects, the whole modeler evolved around this requisite.
Bishop3D comes with a built-in SDL parser and can import a descent subset of POV-Ray SDL code.