there is a guy on ebay sells a homebrew headset tool which makes the job doable. search the forum for ‘homebrew headset’ if that doesnt work try ‘ghetto headset’.
It is worth taking time over though and making sure the cups are 100.00000000000000000000% lined up, and can be a bit nerve-racking (I just did it on my new Transtion frame and I was about as nervous as going shark diving, er first time on the job, witnessing childbrith etc) but it is doable.
If the various headset tools you can get for £30-40 worked with Tapered headset I would have got one of those, but becasue they didnt google led me to here and the £3.99 scally homebrew headset device.
Hurrah for STW
(its the thing Palmer77 linked to while I was writing that)