If you have any spare pieces of the material use them to practice on. You need to get the temperature right so it is just able to deform the fibres, no higher or you could ruin the kilt.

Steam has no effect on man made fibres, so I use a dry cloth, always always always have a cloth between the sole of the iron and the fabric and press/lift/press/lift, do not run the iron along, if you create a wrinkle and go over it with the iron then it is really difficult to remove it - if not impossible.

Never try to get the pressing done in a spare few minutes, do it when you have lots of time.