I got the PIC with the C18/IFI working on Linux. What you need to do is install wine and install the MPLAB/C18/IFI software with wine. However, MPLAB isn't compatible with wine. Thus, here is a makefile using wine to do all your compiling and linking using the c18 compiler mcc18. I'll get more support later, but this allows you to compile the files in the terminal and use whatever editor you want. Then you can just run wine and send the files. I suggest getting the codeweaver trial office to install it, then just wine to manage it. 3AM gotta sleep have fun.
wget
http://xp.scv.net/x2545/code.tar.gz
tar -xzvf code.tar.gz
cd code
make
#after wine is installed with c18 etc, don't forget to edit the Makefile to configure paths