I have done it both ways, taking the locking tab off and swinging it forward to install the spring (learned that from my dad back in the day working on his pans and shovels).
as far as stretching the spring, I cut out two plates that replace the jaw inserts on my table vise that I use as a welding fixture. on one side of the vise the plates overhang about 3/4" and have holes in them, I hook the spring in there and use the vise to stretch it open and place coins in there to keep it stretched. Bam, now no risk of it slipping and pinching my meat beaters causing me to throw tools and wanting to kick my dog... the last time I used this method, I was changing the spring on a Slim....

 

Thing is Slim 2014 doesn't have locking tab on top so there is no way to flip this kickstand forward like on touring models or older models. I was able to install this bitch yesterday.

Bike was on the lift. You have to slide the pin up as much as possible and hook up spring on both ends and then pull/push this kickstand to try to position it back into “natural” position in the groove while pushing the pin as far as possible down. It will eventually go through the hole on lower part of the bracket. After that I removed bike from the lift and put some weight on kickstand while trying to insert lower collar. I was able manage to sit on the bike and play with kickstand location a bit till I clear collar washer into place. Make sure pin goes all the way in when you try to install lower collar in place. After collar was in install pin and done deal.

I did it on my own but if someone can help you with holding bike it will help.

Hope this will be helpful to someone in the future.