replacing heating core on 1995 Buick Roadmaster

How much of the dash has to be removed to replace the heating core?

2 answers
Try one of these resources:
http://bit.ly/autozone_repair_info
http://bit.ly/alldata_repair_manuals 
http://bit.ly/mitchell_repair_manuals_online

Normally, this is a really big job.
Where is the heater core located & how hard is it to change on a 95 roadmaster?