Jak824 you can install this mod by using a tool known as IMG Tool if the files are in "txd" or "dff". Simply find [F2] what the Hamburger Grenade Name [Might be the name of the original file], left click and then right click to Replace with hamburger mod [Extract to Backup] and then go to Commands > Rebuild Archive at the top also as its doing this [Look at the bottom left] and Finally close the program. With SAMI aka San Andreas Mod Installer just open click "Install Mod" be sure to choose the right Where your "San Andreas" folder [Not the User one] then extract the mod you have from its Zip folder and choose "folder" option and install, wait until a screen for the "Donate", "Exit" and "Play San Andreas" appear and your good. one more thing with SAMI the bigger the file the longer it takes.
More funny if it had "Homing Roll" meaning you throw it and it rolls over to the closest target and BOOM! if possible put in a Dynamic Camera that watches the burger as it rolls then a far away shot of the explosion and Special effect of the burger is for everyone you have it restores that much every hour, half an hour or min
I didn't download this mod and you didn't put in a description of how the explosion looks, but can you make the explosion look like meat, cheese, bread and lettuce flying every where.