Howdy folks

I am looking at putting openwrt onto a Cisco Meraki MR18 600-26010.
I’ve been following this guide:
hxxps://openwrt.org/toh/meraki/mr18
I have used an Arduino with a bypassed atmel to get a ghetto serial connection to the device and have been able to start up the limited root shell.
I fall at the hurdle of Flashing Method A step four, running the root.sh script.
This is because the version of Busybox running on the Meraki is 1.01 and doesn’t seem to have all the commands necessary to execute the script which I wouldn’t be too familiar with (I think it’s trying to get full root?).
I put that aside and decided to try and get the initramfs.bin file onto the device, again no go because of Busybox 1.01, I don’t have wget, curl, ftp etc. I’ve seen suggestions that I could use telnet to copy the file off my server (listening on port 80) and echo the contents into a file but I’ve limited experience doing something like that.
I suppose what I am wondering is:
Is it even a good Idea to try and put openwrt over busybox 1.01, could it be unstable? And if there are any suggestions to the above or if anyone else has run into similar.
Thanks for the help on this, the MR18 has been sitting in a drawer for about four years and it makes me feel guilty every time I look at it.