You have to extract them. The .package is a wrapper around the mp3 file, so the file structure is changed and audio players (including the audio libraries in TS2) can't read it.
How hard can extracting be?
1. Open SimPE for Pets.
2. Click the Open button.
3. Browse to the package (path given earlier in thread. Use "Open in Pets" if you don't know where your Pets is
).
4. Right-click the "mp3 or xa Sound file" resource(s)
5. Choose extract.
6. Choose path.
Hardly rocket science…
Mods can't make this work. The game is designed to look for the files in base+locale (or base only for US English), so it will ignore anything in other locales.
Oh I know it shouldnt be hard. Ive never messed with simpe before though. it looked just like a package file is why I was thinking it would transfer over.