If you have a nylon strap with a ratchet (the kind you use for securing stuff), wind the strap around the swingarm and secure the strap over the pillion seat and down to the bracket holding the right footrest, and then you jack up the swingarm to a much straighter line....
Oooo.. that sounds like a good way to lose a finger end LOL... I've already done one finger in cleaning my bike!.. trapped it in the rear brake somehow?.. made a bit of a mess
For both the front and rear ujs, once you have the rubber gaiters pulled back, thread a length of electrical wire through the joint yolk. This will make it easier to hold it in position to enter on the splines.