Transferring Black Ops Map Packs via USB (PS3): Not Allowed—Violates ToS
Do not attempt this. Copying DLC between PS3s via USB violates Sony's Terms of Service and PSN User Agreement. Consequences include:
Account suspension/ban.
Console ban (permanent).
Loss of all digital purchases.
Why It's Blocked
DLC is encrypted and bound to the purchasing PSN account and console ID.
The PS3's DRM prevents unsigned packages from installing.
Legitimate Options
Buy the map packs on the second PS3's account (often cheap on sale).
Game-share: Activate the purchasing account as primary on the second PS3 (allows that console to play the content). Only works with two consoles per account.
Stay within the rules—your account and console are worth more than a map pack.