I do mine just like woodies. If the bend is closer to center just spin in the hand while looking down the shaft and bent/"pump" against the bend, repeat as needed until straight.
Its tougher if the bend is closer to the tip or nock...I still spin/look along the shaft but place the shaft end against a table, tree notch, whatever's handy to apply more pressure.
If the bend is REAL close to the tip I have a hole drilled about 3/4" deep into the edge of my worktable... and simply insert the tip into the hole and bend/pump against the bend.
This approach works for 95% of the bends I run into and after straightening most of the shafts are good enough for practice and 3-D, with nearly all ok for 'fun' shooting (but I don't use re-bent shafts for serious hunting).
I have well-used aluminum shafts that are 6 or 7 years old and still going strong after multiple re-bends and re-fletching. Who says aluminums aren't durable!
(but I still like wood...)