can they be interleaved?

bonus points for capping the length silently.

for me it was the hands, especially the right one as that is on their back.

It needs to be deniable. Actually make it possible for both of you to just walk away without a second thought about it. Alternatively, ask directly (may backfire).

it’s tune-2fs, right

Hence the need to build themselves. It boils down to: download the source, install the dependencies, (configure,) compile, install. In this case, you need make/cmake. You could also crosscompile (on another machine), but that’s trickier. If you’ve never compiled something yourself, maybe start with a known-good configuration from your distribution’s sources.