The races need to be pressed in square. I have done loads and do nto think I have ever made a mess of it. A bit of soft metal or hard wood laid across the top of them stops you damaging them and thencarefull - but with conviction - knock them in - stopping regulaly to see that they are still square - they should be a tight but not difficult job to drift in. Altenativly I have also been luck to get the frame sat next to a drill press in the past and used that to press them in. If you have a spare vice and you keep all things square you can use this as a press too. All of the above will give the proper mechanics out there kittens but the way I see it is it takes loads less pressure to run the race in than it does to damage the race, so if you are careful and are aware that if you are having to use a lot of force, there is probably something wrong, you will not damage anything.
All the usual riders about everything I say being wrong and all ideas are taken on at your own expence and responsibility stand.....
Oh - if they are not taper rollers already I would recommend putting them in.
R