I'm assuming you're talking about https://openrct2.org
If so, it shouldn't be too hard. OpenRCT2 is built on SDL and some open source projects. Luckily, it seems like every dependency library already has a Vita port! Follow the directions to set up VitaSDK: https://vitasdk.org
then get some of the homebrew samples working (especially the SDL rectangle one). Then you can try to compile OpenRCT2 using Vita toolchain (it uses CMake too, so that makes things easy, just do "cmake -DCMAKE_TOOLCHAIN_FILE= $VITASDK/share/vita.toolchain.cmake" and try to compile it). Almost certainly you will run into problems--you can resolve them by either disabling features or by trying to fix them. Run into any cryptic issues and you can ask the #vitasdk IRC room in FreeNode for help.