Hint: Replace USER with your Aegir Octopus system (not ftp) username.
      Your Aegir system username is the same as your ftp username, minus .ftp.

1. Upload or rsync full drupal root of your site to static/custom/name

2. Chmod everything with: chmod -R 775 static/custom/name
   Chmod files with: chmod -R 777 static/custom/name/sites/default/files

3. Add platform in Aegir using full system path of static/custom/name
   so it will be (in this case) /data/disk/USER/static/custom/name

4. Create an empty site in the new platform with temporary subdomain
   like custom-name.your-domain.com

5. Move all files from sites/default/files to sites/domain/files
   with: cp -af sites/default/files/* sites/domain/files/

6. Import your uploaded database (or use backup_migrate module) with:
   cd static/custom/name/sites/domain
   drush sqlc < /data/disk/USER/static/domain.sql
   drush cc (choose 1 to clear all)

7. Rename the site (using Migrate task) to your final domain.

8. Finally, re-verify the site in Aegir. Done!