Hi,
I've just downloaded Irfan View.. Is this the software you're talking about? I wasnt able to get a sequence of bitmaps into one file though, unfortunately there's no help file attached.

As for mine anyways, the whole point is that you browse your input directory, then choose the first file in the sequence. Then you choose your destination file, and the range you want. For e.g. choose Example_001.bmp as your input, and range from 1 to 100, so an image with all bmaps from Example_001.bmp till Example_100.bmp will be created with all images adjacent to each other.
Sorry I dont know how to upload images or files to the forum or else I would have clarified more.
Thank you