OK, so firstly I think you should consider carefully whether nginx will really help you with your performance problem (per your comment), and test that in a development environment before worrying about how your deployment will work.
It is true that nginx is faster, and that it's multi-threaded architecture helps deal with high loads, but yours would be an extraordinarily unusual PHP site if the part of your operation you are looking to speed up accounts for more than one or two percent of the total delays. Your bottleneck will almost certainly be in your database and PHP execution.
You should probably look first at PHP compilation caching (eg APC), a front end proxy (eg varnish or squid), internal caching within your application (is this wordpress? there's some good caching modules there). Handing off delivery of static files only to nginx might be agood idea, but it's probably better to look at using either your own proxies, or a Content Distribution Network for that content anyway.
If you do decide to proceed though, some tools come to mind, albeit they are fairly heavy weight tools. You could use continuous integration and configuration management tools (eg Jenkins and Puppet, or equivalents) to deploy your configuration from a version control repository to your server whenever its checked into the appropriate branch. This is a lot of infrastructure complexity to learn about and build though, and without a good deal knowledge, skill and care, you might as well be just giving your developers root access anyway. Apache's system of delegation through .htaccess has been developed over many years, and you're not going to replicate it's security in a hurry.
Go back and check your assumptions with a profiling tool about how much of a performance issue your regex handling is. I've used mostly Xdebug, but there are other good alternatives.
switch
call in your application rather than a bunch of regexes in the web server. Which, come to think of it, might even perform better...