my tie rod end boots were split all the way around and i used to pack the green lucas grease in them every couple months. then when i had to change my axle seals i went ahead and put some new energy suspension boots on them that i had in the truck for about a year.

revvinram, one thing you can do to grease the ball joints is buy a grease injection needle and stick it through the crack in the boot. the needle only cost about 1.50$ at any parts store.

 

well, anything that sprayable is going to be a little thin. i'd just force in some thick grease. maybe use a mini grease gun with a stiff rod, hold it up to the torn spot and pump it in. try not to get too much dirt in, but don't fret over it if you do.

on some older vehicles that weren't worth investing too much time or money, and where the boot was completely split, i've seen people just wipe in a big handful of wheel bearing grease. grease is grease...

 

I'd probably get new boots, slice it, pack with grease, then zip tie it.
JB Weld or some epoxy mix might work to seal up the crack, though I doubt if they bond very well with rubber.
Maybe one of those cheap tire patch kits is what you need.

I just changed my ball joints last Nov, the boots were so pathetically thin that I ripped them up a bit just installing them.

 

You can actually drill the ball joint carefully and tap them for zerk fittings. It is not the "right" way to fix your problem but in a pinch you can do it. Your biggest issue is whetherr or not you want to take the risk of having it get dry inside and pound itself into oblivion. You could also use the needle technique that Sheriff brought up which will help some in the meantime.