You should be able to trace one of the stalks to the ground and take your garden spade and dig out a clump of soil with it, leaving the roots intact. Put it in some soil, water it in and take it to your friend. It should do just fine. Mint is very hardy. I do this in my garden all the time. Move mint about. It may wilt when first planted, but will stand up the next day.

I don't think you need to bother with Root-Tone, unless you want to. Just yank that sucker up by its roots.