On the easy and cheep, just write a batch file to send a file out the com port.
The first line sets the com port parameters
mode com1: baud=9600 parity=e data=7 stop=1 to=on xon=on odsr=on octs=on dtr=on rts=on idsr=on
type %1 garbage.txt > \\.\com1
The second outputs the contents of a text file to the com port.
Garbage.txt is any text file of 3-4k size that is sent after the g-code, I use to make sure the OS keeps the com port open until the control has finished receiving the g-code.
Save upload.bat somewhere on your system, and then make a shortcut to it in %userprofile%\sendto After that you can right click on a file and select upload.bat and it will output to the comport.