frank said all, but I'll add some easy steps, just to make sure you don't try apply the diff on the OpenTTD trunk version ^^
so, after follow the steps told on the
wiki link
(to install necessary libraries, depending on your linux version), use this steps:
- goto a folder where you want to download the OpenTTD source, open a console window there (Terminal;
- download the source, with
svn checkout svn://svn.openttd.org/tags/1.5.0
- will create a 1.5.0 new folder, where is the source. Enter it;
- download diff file, example with
wget http://openttd.btpro.nl/OpenTTD_versions/BTPro_Client_1.5.0_A_15001.diff
- now you have the source and the diff file, lets apply the patch with
patch -p0 < BTPro_Client_1.5.0_A_15001.diff
- if all goes well, next step is type in terminal
- when configuration complete, lets compile it. I suggest the usage of
- previous step takes some time but when complete will create a new folder, called
bundle where all files needed to run OpenTTD are placed. Since I'm not a Linux user no idea what "make install" command will do, I always use the bundle option and after copy the created files/folders to the desired location. Not sure if the correct way but meh, it works xD
Edit: if you still have issues,
join our IRC
channel
Hope it helps