From the documentation referenced at the question you linked to:
You can use this feature with domains
(e.g. example.com) or subdomains (e.g.
blog.example.com). However, you cannot
specify subdirectories (e.g.
example.com/blog/) or wildcards (e.g.
How do I use a custom domain name on my blog?
Whether Blogger/Blogspot implements a redirect is really up to Google, as Google is effectively your hosting provider when you use that blogging platform.
I'd assume changing your Blogger blog settings to point to the subdomain at your domain (not a subdirectory) would create a 301 redirect, as Google tends to be pretty good about implementing best practices... but keep in mind, you can't use a subdirectory unless you want to proxy requests to the subdirectory on your main domain through to the server where your blog resides.
I need a way to tell blogspot to 301
from each post made on blogspot to the
identical post made on the existing
If that is the case, try this:
- Set up a DNS record for blogspot.example.com to point to Blogspot (per the instructions from that article)
- Complete the blogspot blog transfer (per that article)
- Once the transfer is complete (i.e. example.blogspot.com redirects to blogspot.example.com) change the DNS record for blogspot.example.com to point to your server at example.com
- Assuming Blogspot continues pushing traffic to your blogspot.example.com subdomain (which it may or may not) you can set up a redirect from blogspot.example.com/* to example.com/blog/*