As you said it is for emulating filters. It is not a real filter (like something built in camera you can enable), but just a digital post processing action.
So the image looks similar - it is grayscale and has emphasis on reds, but it wont have the qualities of true near infra-red image (like winter looking foilage).
It works like channel mixer conversion to monochrome, in image processing software.
If you shoot RAW, you can apply this filter later in Pentax Photo Lab.
Technically you need much longer exposure to allow enough true near infra-red light to pass the IR hot mirror in camera to reach usable levels.
Since this is not happening, you can get somewhat similar image by processing the red channel, checking blue channel and subtracting some of the green (to remove the part of red which overlaps with green). This is as far as you can get with post processing. But there is only a very small amount of true near infrared information in this red channel.
That's why i've ordered a real IR filter myself (still shipping
)
Here i've added two images. Shot in RAW - one out of camera JPEG preview, other with the mentioned IR filter effect applied. In addition contrast has been boosted and curves were adjusted to get higher gamma, for maximum IR look. As you can see it is generally just "red" with some other tweaks.: