Sure. How practical it is depends a lot on the cartridge/die.
Cases with signficant taper are pretty easy, straighter wall cases, such as the various short magnums, aren't. All you really want is a FL good die modified so it does NOT touch the case body. I've purchased some used dies cheap specifically as "donors" for that purpose.
Standard FL Dies for cases with a LOT of body taper, such as the .30-30, can easily be used to neck size by simply screwing the die up a full thread or so, no modification needed. (There is no need to size ALL of the neck!)
FL Dies for cases with a .473" head, those such as the 22-250, .243, 30-06, etc., can easily be bored with a cheap 1/2" concrete type carbide bit. I feel it's best to do the drilling on a lathe but a sturdy drill press will work if you are careful. Stop drilling at the shoulder junction, if you don't change that you can still use the die to bump the shoulders a tad if you wish. Other calibers can be drilled with proper sized bits.
You can also bore out the necks from FL dies and make your own "body" dies to be used with Lee's excellant Collet Neck Sizers if you wish. Getting the right size drill bit is a bit more difficult, it takes some grinding and turning on concrete bits that are usually too large.
You MUST use carbide bits to do this, HSS drills will NOT cut case hardened sizer die walls.
