You can do it with tie downs if you wish,but I just used a large pair of vice grips(cushioned with a piece of rubber or cloth to protect the shaft) and clamped down on the strut shaft. Just ramp up the vice grips around the spring to easily take off the spring retainer nut and retainer. Spring just slides off after you remove the vice grips.Loosen the two strut bolts,use a screw driver if necessary in the strut slot to pry open a tad,then easily pull the cartridge out. Install the new one,install a new(or old spring), clamp on the vice grips at the top of the cartridge shaft,turn the pliers and the spring will collapse enough to install the retainer plate then the nut. Then just install the pivot ball and stick it back up into the frame. Doing this almost every day you eventually find little tricks that make life easier.Plus with air tools every job's easier.

 

did you get the springs too? The struts have zero to do with ride height. Likely they are toast too, but they wouldn't cause a leaning problem unless one is seized