Redirects always puzzle me but this guide has been my saviour:
Best .htaccess Tutorials with Sample .htaccess files
However - I think in your case that's not easy. If you click a link with an absolute URL you'd go to the live site. BUT - you don't want to redirect all traffic from the live site to the dev copy (as it would affect everybody)
Only option may be to apply redirects specifically to your IP address? There are examples in the guide how to filter based on IP addresses. You'd need a fixed IP address & then ensure that only traffic coming from your IP is redirected.
There are examples you can use - they are meant for when a webmaster wants to put a site under maintenance, but they give you the basics:
htaccess Tutorial for Apache Webmasters