Transferring email messages from 10.4.11 on PowerPC to 10.8.5 Intel

Question

Can I import all my old email messages from the old iMac G4 running 10.4.11 to my new iMac running 10.8.5?  On http://support.apple.com/kb/HT4889?viewlocale=en_US, Apple says:
     "Note: Copying any data files from your user Library folder to the new computer could have unexpected results."
So is there any way I can move the messages to the new iMac and still be able to read them?  At the very least, I'd like to import all the email addresses I've sent to and received from.  I know I can't use Migration Assistant.
I also have a MacBook (Intel) running 10.6.8.  Would it work any better to transfer to that machine first, then to the iMac? 

Answer 1

Thank you, dianeoforegon.  It seems to have worked, though it created a messy folder structure.  I just hope I don't get any "unexpected results" later.
You can drag the folders out of the imported folder. If the folder already exists, move the messages into the new folder. If the folder does not exist, drag to the On My Mac header and it will sort the folder alaphabetically.
Now should I just keep the old Mail folder on my desktop?  Or can I move it somewhere out of the way?  I can't delete it now, can I?
You can delete.
One more question -- it seems that the addresses in the old email messages don't automatically populate the To: field in a new message.  Is there any way to get them to do that?
First let's go over the basics....
Mail stores your recipients’ email addresses in the Previous Recipients list. To view, under Window in the Menu bar select Previous Recipients. If the person is in your Address Book, you'll see a small icon next to their name. To add to your Address Book, select “Add to Contacts.” in the bottom right of the window.
Copy your data....
On the old computer,
Open Mail and select all contacts in the Previous Recipients List and select “Add to Address Book".
In the Address Book, select all contacts and drag to a folder on your desktop. This will create a vcf file with all your contacts.
Use the same method you used before to transfer to your new computer. Drag the file to the desktop.
In Contacts (Address Book) select File > Import and navigate to the .vcf file. You'll most likely see a window with "Are you sure you want to import xxx cards" xxx cards are duplicates and will be updated.
You can select to Review Duplicates..., Cancel, Import. I would import, then run Look for Duplicates under Card in the Menu bar.
Going forward, keep your Address Book updated. If you sync to iCloud your contacts will be available on all your devices.