Aviation Herald has the link to the final report here:
Crash: Conviasa B732 near Latacunga on Aug 31st 2008, lost radio contact
Report is in Spanish (and scanned in so 48MB in size) but AH has an overall synopsis (not sure the source of the translation).
"
Non compliance of the crew with requirements regarding aircraft configuration, speed and bank angles to carry out the initial turn of Latacunga's instrument approach procedure number 4 as published. That failure placed the airplane outside the protected area leading to collision with high elevation mountaineous terrain.
Contributing was ignorance by the crew during the approach and the lack of documentation governing non-scheduled (special) flights."