Placing screen captures as PNGs (without a file for each one)

I'm using RoboHelp 8 HTML under Windows 7. I have been instructed to make the images (which are almost all screen captures) PNG files. I am struggling to find an efficient method of doing this.

My usual method of working is to compile help files in Word, then import to Robohelp. I capture the images with the Windows 7 Snip Tool, often working with them in PowerPoint before placing them in the Word file. With my current procedure, this results in GIFs in the RH file.

In any case, I need to rethink the approach of placing the screen-capture images in the Word file. I know there are problems importing PNGs from Word into RH8, so I think I want to insert them while working in RH, after importing the text, bypassing any problems with Word.

One approach that I know will work is to save each screen capture to a separate file as a PNG, then insert that file into the RH document. I can do this, but it is slow and results in a separate temporary file for each image--hundreds of files in my situation.

Can anyone suggest a better approach? An ideal approach would allow me to "paste as PNG" into RH, so that I don't need to store every screen capture as a PNG file before I can place it in RH. But I can't see a way to do that. What's a good strategy for me?

Thanks,

-- George