In essence CorelDRAW and Adobe Photoshop are 2 entirely different programs - the former primarily does vector graphics and the latter is primarily raster (bitmap) oriented. I don't know why you would want to do (or retouch) raster images in CorelDRAW..

I suspect they want it in CorelDRAW because they expect you to give them vector as opposed to raster.. if this is the case then may be you should start from scratch and do the whole thing in CorelDRAW..

If for some masochistic reason your print house wants to print raster from CorelDRAW.. then I would suggest exporting your raster images from Photoshop as flattened TIFFs with an appropriate resolution and color model (supposedly CMYK) and importing them into CorelDRAW.

If imported into CorelDRAW as PSD it preserves layers but some of your effects will be gone (such as drop shadows, etc). Experiment with it.

CorelDRAW allows you to manipulate and do quite a few things with imported raster images but, of course, its capabilities with raster are not nearly as rich as those of Photoshop or Corel Photo-Paint.

Of course, you can combine these methods... or have part of the file as vector and retouch included raster images in Photo-Paint (that comes with DRAW).. that way you'd be able to apply masks and do all kinds of stuff that a raster image program normally does to an image (get them back into CDR just the way you want them to look)...

PS: always remember (correct color model + appopriate resolution + flattening when necessary + try learning to use color management in DRAW).. because inadvertently left-over RGB raster printed from DRAW looks really ugly.

Hope this will help.