I’ve done it despite not knowing much about it and it worked out fine. The most important thing is to find the correct quality nut files for the job, and they’re not cheap. Actually good nut files cost a pretty penny. So if you only have one guitar you want to slot a nut for, drop it at a guitar tech. If you have many guitars or plan to have many guitars, then you can buy a set of files.
Really and to me, it’s the cost of the good files that’s more of a deterrent than the handwork in shaping and sizing a nut to fit your guitar. It felt like a waste to me when I basically don’t really plan to have guitars without a trem in the future, as trem guitars don’t usually ever need any slotting.