Try IRQ 7
EDIT: Here's an installation guide for the game itself:
1. Take the game install files and extract them to a folder that you mount it in DOSBox (can be a subfolder).
2. Switch to the folder in DOSBox and type INSTALL.
3. First the setup asks for the source folder, this should be correct by default, so just press enter.
4. The game automatically installs to C:\Mirinae\RPG\ (in the DOSBox file system). After installing, you can move the folder wherever you want.
5. During the install process, the game asks you several times to insert the next floppy. Since you're likely using the CD-ROM release, just press enter and it goes on.
6. Next up is sound configuration. Chose the first menu point, then the second (the one with the "100%" in the text).
7. The second through fourth menu points are the usual Sound Blaster setting. Set the adress to 220, IRQ to 7 and DMA to 1, then go back with the bottom choice.
8. Chose the second point, then once again the line with the "100%".
9. The third menu point saves the settings and quits.
10. Quit DOSBox and run the Romance_of_the_Forgotten_Kingdom_English_v09.exe
11. Just browse for the folder the game is installed in and click "Install".
12. Start DOSBox, go to the game directory and type PLAY.