There have been plenty of posts dotted around the Magento community helping to get a local testing version of Magento set up on your machine, but here is a quick tip (as a reminder to me too!) Try this installation guide for a quick start. Once you have got Magento installed, you can download all the site files for your store via ftp and install the database.

Next, open up your /private/etc/hosts in a text editor. (I use Text Wrangler from Barebones software). You can get at it by going to File > Open Hidden… and navigating to your main Macintosh HD drive.

Edit the file so it looks something like this:

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
fe80::1%lo0 localhost

# my websites
127.0.0.1 www.localhost.com
127.0.0.1 http://www.localhost.com/magento
127.0.0.1 http://www.localhost.com/mywebsite

Once you have done this, you will need to edit your store database to reflect this. Go to the database and do a wildcard search (%mywebsite%) on the core_config_data table.

Edit both the web/unsecure/base_url & web/secure/base_url fields so the value is:

http://www.localhost.com/mywebsite/ making sure the trailing forward slash is there!

Restart MAMP and you’re good to go, using your new url to check out your site