Another way to convert your custom string into an electrum wallet is to do a sha256sum md5sum of it. If you are on a nix system:


It will output a hexadecimal number. Then run electrum, select restore from seed and paste in the hex to create a wallet.

edit: 64 hex digits from sha256sum doesn't work in the latest version of electrum. It will only work if you have 32 hex digits i.e. an md5sum.