It's true you can use a nullmodem cable, but that only works if you have some kind of terminal software on your amiga already. If you don't, how are you going to transfer it?
Additional terminal software is not required to intially get transwarp on to your Amiga system.
As stated above, the Transwarp application can be sent from your IBM PC and copied to disk or ram disk as follows...
1.) Set serial port prefs on amiga to match those on IBM PC. (it might be best to start at 19200 baud. You can experiment with faster speeds later.)
2.) Run ADF Sender Terminal program on IBM PC
3.) Now at cli issue the following... copy SER: RAM:Transwarp
4.) On the IBM PC select the Transwarp file and send.
Once transwarp has been transferred to the amiga, you can then use it to transfer ADF files from the IBM PC to 880K disks on the Amiga or the other way around. From the floppy to an ADF image file on the IBM PC.
-AmigaEd