I doubt you will ever get smooth scrolling in DOSBox. Most Windows desktops and LCD monitors are set to 60Hz. But DOS Games run at 70 (at least that's what my monitor reports on a DOS machine). So there is a mismatch.

Even when running a lower screen resolution at 70Hz, scrolling still isn't smooth. I guess this is because smooth scrolling isn't a priority / people don't notice it and because the PC was more for Adventure games, 3D Games and simulations and scrolling games more on consoles.

If this game is available on a console, just play it there (SNES or Genesis). Make sure it's the NTSC version at 60Hz so that you get that super smooth scrolling 😀

The smooth console emulators speed up / slow down the game a tiny bit (like 59.989 Hz or something) so that it matches the refresh rate of the windows display.

Under DOS (there are heaps of emulators for real DOS) you could just display whatever refresh rate you wanted (good old CRT technology) so there you also had super smooth scrolling.

EDIT: Tried on my time-machine PC and there it also has tearing. So I think it's just bad game / programming. I checked on Wikipedia and the Virgin version was for Sega Mega Drive (which is PAL 50 Hz). So I think they just ported it sloppy to the PC.

Now PAL 50Hz games you can't get smooth on modern Windows PCs with LCD monitors. With lots of trickery and CRTs it's possible though. There is also an Amiga version but this one is also PAL 50 Hz 🙁

So your best option is to play on a real European or PAL Sega Mega drive!