C should be fine for working in DOS. What compiler do you have ?
For some DOS LCD programming in C you might want to check the MPXPLAY sources:
http://geocities.com/mpxplay/
MPXPLAY uses Watcom C and the parts needed can be downloaded for free. Somewhere at the MPXPLAY site there are instructions what parts are needed to compile MPXPLAY and how to do it.
For some SED1330 examples you could check the lcdproc project for linux. It has sources available for a SED1330 driver. I think there were also other more simple SED1330 examples available but I just can't remember right now.
The SED1330 datasheet from EPSON has some initialization examples and then there is also some app note from SEIKO that has initialization examples. I think it was called builtin1330.pdf or something like that.