I've encountered this sort of issue several times over the years and there are several possible cures. Generic things to try:

1) Assuming it a lower joint, put the jackstand right under the ball joint to force the taper into the eye. Sometimes works.

2) Smack heartily on the bottom of the joint - I use a lead hammer but if you don't have one use a block of wood (hardwood like oak preferred) and a BFH. Use care not to mess up the Zerk fitting hole or get junk into it, if so fitted.

3) Shanghai an unwilling accomplice to pry the control arm onto the taper - this one often gets the job done.

General advice - don't fret TOO much over the torque. Most shops will pull this connection up with an impact. Besides, if there's a cotter pin, you'll have to move the nut to the next slot anyhow so the torque will be higher than the spec. Sadly but not surprisingly, my Haynes manual shows nothing on this so I don't have details on this particular installation.

Dan