Gear linkage dust boot cover

Hi All,
 
Searched around the web for info on replacing the gear linkage dust boot cover (not sure if correct term) but could not find anything. I found the dust boot cover easily enough from amayama but was struggling with replacing it.
 
I don't have an actual picture of it at the moment but those that have done the shifter bushing (to bearings) replacement for improved gear feel and square bushing should know roughly what I'm referring to. It looks similar to the picture below. Has anyone replaced this? How did you get the boot in? I can't get the bolt just before it to come out so the gear fork and square bushing housing from the boot onwards won't come off and prevents the boot from sliding in.
 

Yeah that " bolt" is actually a cotter pin like in the pedal crank of a push bike.   Support the shifter shaft then with the nut protecting the end of the thread give it a good solid whack with a smallish hammer.  Should get it started then use a pin punch to drive it right out.
That first photo is rubbish as some of the mechanism is arse about face.  Don't use it as a reference.

Yep.   But as previously stated it is well advised to support the shaft against the hammer action.
Loosen the two bolts holding the bracket to the top of the gearbox  (Under the starter motor ) Raise up the front of this bracket to remove the square bush and the selector crank should slide off.  Pretty straight forward really.
Bit of Inox is good too.  Some grease smeared on the selector shaft before the dust boot and crank go back on will make for an easier job next time too.   Go to it.
Cheers.

An effective method for removing stubborn cotter pins is after putting the nut on to protect the thread as dasic says, use a small 'G' clamp with the fixed end of the clamp on the nut, and a small socket on the opposite side of the crank to allow the cotter pin to come out.
After doing up the clamp as tightly as possible then tap the fixed end of the clamp. It should pop out