Lift it off with the 3-pt lift, set it on several concrete blocks, or a stack of wood, or planks over stacked firewood,, anything high enough off the ground to give you slack in the chain,, then reattach with as much chain as you can,, and set on the ground, or repeat the operatiion...
I usually have a stack of concrete blocks around,, just make a 2-high or 3-high stack, with a plank across them..
WHATEVER you do,, DON't put yourself in a postiion for the boiler to tip off the stack and fall on YOU!! Especially if you are alone!! Put your cell phone in your pocket !!
I remember a friend looking at a setup I was about to set in motion.. He said,, just a minute,, let me dial 91... and keep my finger over the number 1.. 'cause that contraption looks like we're gonna need help !! I laughed and rebuilt the setup.. and 911 wasn't needed..
Safety first !!
Congrats on the purchase... that should do just fine for your needs..