You can use various protocols but they are not included in MSComm. You will have to either use a different tool, find some source code or write it yourself.

I use Sax Comm, and have used PDQ Comm, both work very well and include a terminal program as well as several major protocols.

Using MSComm you can simply read a block from the file using binary access and send that block to the remote which should then write it to the target file, appending each new chunk as it arrives. The problem is that sometimes you may get an interuption or noise on the line which can cause the block to be different than the original.