Hi,
Yes, the DTR signal is used to remotely reset the PIC but you can easily use it without that feature, I do that all the time on one of my developement boards from SURE electronics. I hit Program and it asks me to reset the device - which I do - and it downloads the code to the device.

When it doesn't work it's usually because I've specified the wrong COM-port which happens to me from time to time, especially when using USB->COM dongles/adapters.

It's important that you flash the PIC with bootloader.hex file for the correct oscillator speed (20MHz in your case) and that you put DEFINE LOADER_USED 1 in your program.

/Henrik.