I want the process to look like:

1. I choose the correct scan settings (dpi, color depth, etc)
2. I lay the first page on the scanner and trigger the process
3. The scanner scans the page and waits for me to position the next page correctly
4. I confirm that the next page is ready for scanning
5. Repeat the above two steps until I tell the scanner that there are no more pages to come
6. The scanner saves everything into a single PDF.

I tried both xsane and gscan2pdf. First problem: they want me to know how many pages will be scanned. This is already a nuisance, but I can do the counting if needed.

The main problem is that in step 3, the scanner does not pause. It is probably optimised for being fed loose sheets. The next scan process is triggered automatically as soon as the CCD has returned to the start position. The time the scanner needs to return the CCD is very short and I can't turn the page and position the book properly.

Is there a software which can do the scan process in the way I described above, or did I just miss a setting available in xsane or gscan2pdf to make the scanner pause?

If it makes any difference, the scanner is an Epson Stylus SX620FW, I run it using the manufacturer-provided driver.