I'll tell you step by step what I've done:
I started up the MG Editor -> Save file mode -> Import PCD -> PGT From WC -> SAVE ->Action Replay Export -> Live ARDS Code preview (I set it to Platinum EU Gift 1) -> copied the code and manually put it in my AR... I think I failed there.
And about the Yellow Forest card, I can just put what ever I want as the code? So I could make the code something like: I like pie except when its fake ? Or does it have to be as random as normally, like FAHSH211 HYYYWJK1 etc? And how long should it be?
Also, I don't really understand what you meant with the copying things in the blank xml.
For example, here is the Jirachi XML before I put it in AR:
EDIT:
Seems like the weird </game> things and such are gone in the spoiler thing, is that a big problem? They're there in my wordpad document
EDIT EDIT:
Yellow Forest problem (gosh I suck, sorry for annoying you guys with mah stupid questions):
I imported the PCD, pressed from WC and saved PGT. (Corresponding WC number = 1)
I went to Action Replay Export, Custom IDs = Pokemon HeartGold UK - HGSS, JP (IPKE AD102382).
When I click the Custom ID, I get an error message which says something like "The value of -1391451262 is not right for Value. Value has to be between 'Minimum' and 'Maximum'." --> Sorry, it's not the exact translation, but I translated it as good as I could. Also, my Live ARDS Code Preview is still 'Diamond - JP - Gift 1'. Should I change that? (If I change it to EU HeartGold it says it's "Index is outside the Matrixborders" or something --> Terrible translation sorry... I had to translate it litteraly word for word, I hope you guys understand)
Sorry for being such a difficult person >.<