Well, thank you all. Now if you're interested, here's the procedure.
First, you make two shots, on a tripod, of the same scenery. Has to be quite static, of course (here, I knew the water was moving fast and I was anticipating the effect of its smooth flow). Take one of the shots with an IR filter on, the other w/o. Just make sure you have the best exposure in both cases, that is, don't bother with any compensation.
Open the colour - standard - version in PhotoShop and convert it into the LAB mode ("Image - Mode -..."). Hold it there.
Next, open the IR version in PS and convert it into a B&W version, using any procedure you feel comfortable with.
Once you're satisfied with the B&W rendition of the IR picture, select all of it ("Edition - Select All") and copy it ("Edition - Copy").
Switch back to the open colour version you have converted into the LAB mode previously. Open the channel window ("Window - Channels") or palette and in it click on the Lightness channel to select it.
Now, you are going to replace that Lightness channel (which is in grayscale) with the B&W rendition of you IR shot. You have previously copied this, so it sits inside the temporary memory of your computer. To paste it, do this : First "Select all". The entire grayscale image of the Lightness channel is selected. Then use the"Edition - Paste Into", and voilà, the B&W IR replaced the Lightness channel.
After the conversion, switch back the mode to RGB ("Image - Mode - ...").
You now have something different you can tamper a bit to your taste, and for our pleasure.
I hope I made it clear enough. Anyway, if you want to know more, just PM me and we could Skype. Else, I'm waiting to see some of your own experiments too.
