Progressing from single bar dip to korean dip

I'm having trouble progressing from single bar dips to korean dips.

I can do 5 x 5 reps of single bar dips (over and under grip), but can't do a single korean dip.

I've been doing some bastardised assisted Korean dips of my own invention.

I'm not strong enough to press up on my own, so I've been hopping off one foot  until I can press and lockout in the top position.

I try to lower myself slowly, but once my elbows go past 90 degrees, I callapse

Can anyone suggest some intermediate exercises I can use to build up uto Korean dips?

It could also very well be a problem with my single bar dips. I don't think I've been half-arsing them, but I welcome any tips for running a self check on my form.

 

Here are two other threads on the subject that have some really good pointers.

 

1.  Korean Dips

2.  Korean Dips....ow ow ow

 

Off the top of my head the only pointers that I may be able to give you is do your best to keep your elbows pointing backward and push your hips forward to keep from hitting your butt on the way up. In a way Korean dips are like the Bench dips(HBP/PE4) of Foundation 1 except your legs aren't supported. 

 

Without any videos or series of pictures to look at it is fairly hard for anyone to give pointers.

Take some video and post it here. The move takes more timing and flexibility than strength IMO. Try and arch strongly on the way down. If you can do them with gloves if you are outside. Get chalk if need be if you are in an actual gym. It takes some time to adjust to them. And once you can do them your body becomes angry at you for this new move you ask it to do. The IM is great!