cut my own hair through few years of college.
a sheer thinner, a buzzer, #1 near the neck, #2 near above, and then eventually #3 will do the job on the side, then haircutting down to 1" with a thinning sheer will probably do the trick in most cases.
but eh... sometimes you may miss a spot, or two.. or three.
and then the clean up is a big mess unless you have a good, wide-open space in your house... I no longer does though....
will probably have to live with #1 for the side burns for the time being.
edit: Please note, if you are not a professional... like I am ... it's easier to start with the longer hair you want to save, then move down.
This means you actually go with the opposite of what I mentioned. top hair first. higher mm buzzer setting around the head, then gradually lower the mm toward the bottom
easier to blend hair this way.... starting with longer hair will allow more room for mistakes.