Something like this.
If you plan to actually use this port, it may be worth checking which was the last version to support SDL1. Current one does not seem to, judging from setup.py at least. I am not gonna dig into this myself. You may check through commit history of pygame itself, or/and its port, or perhaps just ask developers to help you, they probably know when support was dropped. Once you know, then either pick an older portfile from history, for that specific version, and make sure to set it to use SDL1, or edit the current portfile (possibly replacing version and checksums can work). In the worst case I can handle a portfile for you, provided you find out which exactly version you need.