Geocaching on Android...

[JustAlan]

Sussed it - Found the info on the neongeo website, you use the Personal Cache Note feature  ->

To make use of the PCN function, the first thing written in the PCN on the cache page must be the corrected coordinates. Additional notes and coordinates can be included after this for personal reference, but any other coordinates will be ignored. To add or edit a PCN to a cache :

Go to the cache description and select Edit¨Personal Cache Note to add/edit the PCN directly from Neongeo
 
When the full cache details are loaded/refreshed in Neongeo, the cache will be shown with the new updated coordinates

[The Tares Clan]

You can also add a PCN in the field.

If you go to a geocache and press Menu->Edit, you can select Personal Cache Note.  If you are online, this is automatically uploaded to the PCN in GC.com. 

It is best to use PCN for corrected co-ords.  As JustAlan says, if you put the corrected co-ords first in the PCN, Neongeo will automatically update the cache co-ords to match the corrected ones and will show a green border around the cache symbol on the map page.

If you use the pencil icon on GC.com, there is currently no way to know that you have corrected co-ords in use.