Grand Theft Auto 3 for the Dreamcast - DCA3 Alpha Version Now Available
Fortunately, compiling instructions are available. So, as long as you are capable of following these, have bought a copy of GTA 3 for PC (Rockstar offer a digital version with Vice City and San Andreas for a reasonable price), and have a Dreamcast that can play burned discs or has an optical drive emulator installed, then you should be good to go.