feeded→seeded as it seems to be the term used in other tickets to designate editing through URL with parameters.

You're trying to add an ISWC on the ISRC page...

To add an ISWC you have to POST to e.g. http://musicbrainz.org/work/0a925fa3-98a9-43fc-8a0e-071726fb7af6/add-iswc with the parameter add-iswc.iswc=T-030-066-497-4

This doesn't allow seeding the form, however; that's still an issue if you want to show the page with a pre-filled iswc and allow the user to add a comment before submitting.

I update the URL as I mistook the paste.
I have tested http://musicbrainz.org/work/0a925fa3-98a9-43fc-8a0e-071726fb7af6/add-iswc?add-iswc.iswc=T0300664974 both POST and GET nothing happens.

OK this is not really urgent stuff as it actually works to make a POST request to add any ISWC ! I leave the ticket here in case it's useful but lowering the criticity.

The page for adding ISWCs is gone, so editing the summary.

nikki, the new work/create URL does works with new ISRC parameter(s), either POST and GET (both tested with userjs).
I did not try the new work/edit URL yet but it could be working too.

An example would be nice then. It didn't work for me when I tried.

GET example : 奇子
POST example : You would have to install my JASRAC importer and go to 奇子 and click Add to MB button next to work name.

Thanks. Closing as invalid then, since the add ISWC page no longer exists and the add/edit work pages appear to already support it.