found them with grep, though:

1:53 spiceman@cynic ~/perl5/lib/perl5 % grep -R 'sub add_columns ' DBIx
DBIx/Class/CDBICompat/ColumnGroups.pm:sub add_columns {
DBIx/Class/CDBICompat/ColumnCase.pm:sub add_columns {
DBIx/Class/DynamicDefault.pm:sub add_columns {
DBIx/Class/TimeStamp.pm:sub add_columns {
DBIx/Class/ResultSource.pm:sub add_columns {
DBIx/Class/ResultSourceProxy.pm:sub add_columns {

1:53 spiceman@cynic ~/perl5/lib/perl5 % grep -R 'sub table ' DBIx
DBIx/Class/ResultSetManager.pm:sub table {
DBIx/Class/ResultSourceProxy/Table.pm:sub table {

1:53 spiceman@cynic ~/perl5/lib/perl5 % grep -R 'sub load_components ' .
./Class/C3/Componentised.pm:sub load_components {