Using a PC mouse without a h/w adaptor?

[AmigaMance]

Hi, ppl.
 I have a PC mouse which has exactly the same plug with an Amiga mouse (actually, the original plug is a small round one that adapts to an "Amiga-like" plug) and i want to ask you if there is a way to use it, without a hardware adaptor. I hope there is a software driver for this.
 Right now, when i plug it in without touching, it makes a constant hick-up move and the LMB reacts like it's been pressed on and off rapidly.

[AmigaMance]

 I see. But where would i connect my modem if the serial port is occupied by the mouse?

[AmigaMance]

 Yes, a mouse-port adaptor would be ideal. I think i will buy one asap.