A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 5 November 2007
I announce I'm playing a Will, target a dead Samurai in my discard pile, and pay his gold cost using Supply Outpost.
May I use the Supply Outpost effect to attach a card from my hand to the resurrected samurai?
This rules question actually happened during the European Champs.
Will: Dark Virtue Battle: If there are any enemy units at the current battlefield, target a dead Samurai Personality you own: Bring him into play there, paying 2 less Gold and ignoring Honor Requirements.
Supply Outpost: Bow this card: Bow this card: Produce 2 Gold. If this pays for a Personality, you may attach a Follower, Item, or Spell to him from your hand after he enters in play, reducing its Gold cost by 3 until it attaches.
Martin Lund (rules official), 9 November 2007
I announce I'm playing a Will, target a dead Samurai in my discard pile, and pay his gold cost using Supply Outpost.
May I use the Supply Outpost effect to attach a card from my hand to the resurrected samurai?
This rules question actually happened during the European Champs.
Will: Dark Virtue Battle: If there are any enemy units at the current battlefield, target a dead Samurai Personality you own: Bring him into play there, paying 2 less Gold and ignoring Honor Requirements.
Supply Outpost: Bow this card: Bow this card: Produce 2 Gold. If this pays for a Personality, you may attach a Follower, Item, or Spell to him from your hand after he enters in play, reducing its Gold cost by 3 until it attaches.
Though Will has a * in its Gold Coin, the cost of the Personality is the cost of the Personality, not Will.
Consequently, Supply Outpost is paying for the Personality, and will give you the change to attach something at reduced cost.