Migrate 8.0 dump to 7.4

Hi,

I have a dumpall file generated from a 8.0 version that I need to import
back to a 7.4 server.

Is there a way to do that?

a psql -f db.out template1 gives me
psql:/tmp/db.out:687: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:697: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:707: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:717: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:727: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:737: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:747: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:757: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:767: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:777: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:787: ERROR: syntax error next "INDEX" at character 7
ALTER TABLE
psql:/tmp/db.out:797: ERROR: syntax error next "INDEX" at character 7

Any idea?