At the moment it’s not possibly to use your own/existing keys. It may be possible in the future.
The custom keys-link is visible when you edit a post and have enabled simple fields for that post.
Thread Starter
mobe
(@mobe)
Thanks Pär for the quick reply. Can’t belive this is the fourth Custom Fild Plugin wich I tested doesnt support using existing custom field keys.. Makes this kind of plugins useless for most scenarios were you want to enhance your existing Blog with Post Editor Forms for custom fields. Definitly a feature you should implement.
I stick to custom Code in my functions.php as decribed here:
http://www.deluxeblogtips.com/2010/04/how-to-create-meta-box-wordpress-post.html
For others searching for a Plugin Solution: “Custom Fields Creator” and “Meta Box” seem to support existing custom Fields.