I imagine you are going to wind up with about a 20 megabyte file. Some scan software lets you scan into an existing file, some doesn't.

There is a pretty simple work around, use Microsoft Word and paste or insert (better to insert) the scanned images into the Word Document. Just save a blank Word document, making sure to widen the margins left, right, top, and bottom to about 0.2" to give you as much space on the page as possible to hold the images. From the "Insert" drop down menu, choose "Picture" and "From File" and you can browse to your scanned images and dump them in there.

You may even have some success in manually decreasing the size of the scanned pages a little, or even putting two on the same page. If the scanned pages are Portrait, try going Landscape with the Word document and putting two on the same page.

Another idea is to use an application that has "OCR", optical character recognition. This will convert the text of scanned imges into editible text that you can put into a text Word document.

Either way, you are going to be spending a good bit of time on this project. It is not something that you are going to accomplish in ten minutes, more like about three hours.