There is "crinkle paint" that can achieve the textured effect on the front of the keyboard.
I have only a very small amount of black, that I got from a guy in Britain who claims that he got it from a guy who restores old cars. That is the only lead I've got, I'm afraid.
It could be a bit tricky to use, though, because the thickness of the layer of paint defines how large crinkles that will form when the paint dries. I was painting a cylindrical object, and I quickly learned that I could not paint it in squirts from three sides -- the areas where my painting overlapped got crinkles that were three times as large as the others! I had to build a motorized rig to be able to paint it in a single sweep. I suppose that painting just the top of a keyboard would be easier to do in one sweep.
Another method could be to use epoxy putty and a rubber stamp. First lay some latex rubber or silicone onto a piece of textured plastic and let cure. Then lay down epoxy putty on the area that you want textured, wet it thorougly (because water makes epoxy putty soft and slippery) and press your flap of rubber onto it. If it does not look right, you can smooth over the epoxy clay/putty and try again.
On my Compaq MX-11801, I did not care about replicating the texture, as it was quite fine. I used only ABS (from cut off pieces of the case) dissolved in acetone as putty and then filed and sandpapered it smooth. I figured that I would paint it with Vinyl Dye, but right then the supplier of the chain of shops that I was going to buy it in decided not to stock it any more ... and I can't find another source of it in Sweden. Gah!
I doubt that the stamp method would work with ABS/acetone sludge, though. ABS sludge needs to cure properly, and it changes it shape while it does so. Be extra careful with ABS sludge so that you don't lay on too large 'a layers -- that may never dry. It can also shrink considerably when it dries.