Specify locations of custom symbols in ~/.gEDA/gafrc configuration file:

(define gedasymbols "/data/smb/users/dambi/projects/gaf/sym")
(component-library (build-path gedasymbols "analog"))
(component-library (build-path gedasymbols "connector"))
(component-library (build-path gedasymbols "linear"))
(component-library (build-path gedasymbols "micro"))
(component-library (build-path gedasymbols "misc"))
(component-library (build-path gedasymbols "power"))

• make a text file called 'attribs' listing the attributes you want in the BOM, for example:

$ print "device\nmanufacturer\nfootprint\nsupplier\npn" > ./attribs
$ cat ./attribs
device
manufacturer
footprint
supplier
pn
$

No need to explicitly specify 'refdes', it is always added.

• Let gnetlist create the BOM and sort it using 'refdes'

$ gnetlist -g bom -o file1.bom file1.sch
$ sort -o file1.bom file1.bom

Tabulator is used as a separator in this case. There is also a possibility to generate BOM with colon used as a separator:

$ gnetlist -g bom2 -o file1.bom file1.sch

gEDA project
gEDA Wiki
gschem symbol creation guide
Repository of contributed symbols and footprints
pcb project
PCB-20110918 manual
pcb footprint guide
Footprint creation guide