You can't do that on a computer and then transfer them over? That would annoy the hell out of me.
If you really want to get the full "Dark Tower" experience you really should read as many King novels as you can...
http://en.wikipedia.org/wiki/Stephen_King_works_related_to_The_Dark_Tower_series
I would specifically suggest you read hearts in atlantis before reading the Dark Tower 7.
http://en.wikipedia.org/wiki/Hearts_In_Atlantis
http://en.wikipedia.org/wiki/The_Wind_Through_the_Keyhole