This is what we did, and what we learned:

1. Created an SQL dump using phpMyAdmin.
2. We changed latin1 to utf8, changed the tables to InnoDB, and also changed the default encoding for en_CA to utf-8, so which will help normalize data in future.
3. We tried to upload through phpMyAdmin. Our cress version allows files of up to 15 MB (ours is ten), but the PHP timeout proved too short and only part of the file was imported. We deleted the tables to start again.
4. We went to the mysql command line on cress, and tried importing from there. The first attempt failed because of the utf-8 BOM (presumably PHP had disposed of that when we used phpMyAdmin).
5. The second attempt, with a non-bom file, also failed with this error: "got a packet bigger than max_allowed_packet". We found documentation on this here.
6. We called Ryan to have him increase the server and client settings for max_allowed_packet.
7. Ryan was too busy to respond quickly, so we decided to try a new approach. We did a new dump using mysqldump, like this:
   
   ./mysqldump -u tapor -p --set-variable=max_allowed_packet=16M hcmc_b2evolution > /home1t/hcmc/b2_bu.sql
   
   This dump is set to break up the sql appropriately for the default package size.
8. Again, we edited the file as in (2) above. We also, for good measure, changed the encoding for Swedish to utf-8 to catch any instances of posts going into the db with that encoding. We saved as ANSI (so there's no BOM, but the UTF-8 encoding is preserved).
9. We did a restore into mySQL 5 like this:
   
   ./mysql -u hcmc -p hcmc_b2evolution < /home1t/hcmc/b2_bu.sql
10. We changed the base url in conf/_basic_config.php to point at lettuce, otherwise links on the site always go back to the old site. We may later have to change this to hcmc.uvic.ca/blogs in order to get the blogs functioning as if they are part of the HCMC site.
11. We tested posting, reporting, languages/character sets, and so on.

Still not finished: update of CSS, which is a bit borked because it appears that some class names may have changed.