The only possible solution I see is to transfer your bytea in chuncks.
Split your file in say 64k block and transfer them to the database with:
insert into wavs (data,id) values (xyz,chunk1)
repeat
update wavs set data = data || chunkn where id=xyz
until finished
If you want to do the same for reading the wav's back from the database, change your table layout to store the numbered chuncks instead of the complete wavs.