mac pro G5 boot issue- Leopard and Yellow Dog 6.2 installed
Problem solved! So, I decided that, since Im desperate, Im gonna do what I have to. I deleted the partition with Yellowdog on it, then messed with the firmware a lot. I managed to find a way to get it to boot straight to MacOS... and then used Cmd-S to boot into single usermode and surprise surprise, AppleJack rescued my machine in 4 passes. 

Incidentally, after I managed to get the machine sorted, some kind soul sent me a Leopard Install Disk. Retail. 

Nice!