This post helped me yesterday. I run my HDHR-DVR on a Mac as well. (Thanks jasonl !)
I initially tried using the Unix commands and it did not work.
Next I decided to go with editing the configuration (".conf") file. But first I had to get info on the file only to find my local account was not listed to edit (read/write) changes to the file. I unlocked the properties using the lock icon below. I then added my account to the file with read/write privileges. I copied the file HDHomerun.conf file. Opened the file at the copied location. I changed the location from my boot drive to an external 8 Terrabyte USB3 drive.
I saved this file. Then copied it back to the original location on within the installed location on the boot drive. (Inside the Users/HDHomeRun directory.) When asked, I replaced the original file.
Lastly, and most importantly, I immediately REBOOTED the computer so the configuration change would go into effect.
I tested the change. I opened the HDHomerun folder on my external 8 TB drive. Then expanded the LIVE TV folder so I could see its contents (currently empty). I finally opened the HDHomeRun app on the Mac. (It could be opened on any device.) A channel began playing. Within seconds, I saw a file appear in the Live TV folder. I exited the app, turning off access to the tuner, and within seconds the file in the Live TV folder was automatically deleted. I tested further by opening a show and saw the oldest episode I didn't plan to keep. I played the recording within HD Homerun via an iOS app. The recording played fine. I then deleted the recording. It was purged from the Mac directory within seconds of this.
I hope this detail helps!
My next issues are audio getting out of sync in Live and recorded shows. My Mac Tower has a lot of RAM and is wired to a gigabit switch. TV devices are also hardwired to the network. My Mac by default is not USB3. I'm going to pop in a USB3 card in hopes faster access to the drive will remedy the audio issue.
After that, I use both HDHomeRun and the Channels apps. Sometimes the Channels app sees OTA stations that the native HDHomerun app does not see. (I like the Channels app guide but not their pricier DVR service.) I can't figure out as both are using the same tuner and broadcast feeds why one would drop signals while the other does not.
I have ripped my DVD's to my hard drive for years and shared them via iTunes to AppleTVs in the network. But I'm also now using FireTV and Roku to be educated about the user experience. I'm using Plex as an alternative to share all content (recorded broadcast shows and movies, ripped movies, and my music and photo collections.) I love cutting the cord and HDHomerun is my champion. I'm evangelizing in all other forums about it!