If you don't have installed the bottom bracket and the headset, you can easily do it without the white straws.
Entering to the rear.
Helping it go over the BB shell with your fingers.
While you push from the rear, you can always help it move with your fingers
Then from the headset hole, you can guide the brake line out of the left side of the frame.
For the bleed, since you will probably have to cut the tube.
Even if you loose some drops, during the operation.
If you make a nice cut, you reach the liquid again.
And one thing to avoid, is to touch the lever while it is disconnected.
This will throw all the liquid out, and you'll have to bleed it for sure.