Hi Ddraig,
I have successfully done what you are trying to do. I'll try to describe what I do when I update the DB because you'll need to have full control on your host/ live site. I also have locally SQL Server 2005 Express with Advanced Services installed, and my host has SQL Server 2005.
1. first of all, you will need to add the correct alias to the PortalAlias table in the DNN DB; it should at least have two for each PortalID: one for your local path (without using http:// nor pointing to the page, just the directory where default.aspx lives is enough) and the other for when the DB is live. Make sure the live alias is the correct one!
2. before I make a backup of the DB locally, I run some scripts to change the image paths for the modules that use HTML content, images, and also javascript that gets injected is checked
3. then I make the backup, zip it and upload it onto a folder on my website
4. then in my panel I browse to my SQL Server 2005 DB, and select RESTORE (my host on www.dotnetpark.com does luckily provide this very useful option)
5. I point to the zipped DB, and press Restore button, and voilá
6. all DNN logins work, the alias is correct, and also the image paths are correct, the only ones that I haven't tackled yet are the ones inside the templates
I hope this makes sense, if anyone is interested I can post an example of the script I'm using to change image paths.
PD: this procedure may fail if the host has poor DB support, currently I am facing a similar case, so please take care in choosing your DNN host!
PD2: I do all this stuff because I need the dev process afap (f=fast) and it works really great for me!
Cheers, Pieter