children of COB
Deadnight Drinker
that honestly seems impossible if you're playing a fast lick, like 16th note triplets at 120bpm.
Was more like a joke answer, of course you can't bend the 21st to a 24th while playing leads. Also, you really have to have really strong right hand fingers to bend a 21st into a 24th while doing a sweep tap, don't want to think about it

Sorry, forgot to answer this!
When I first starting thinking "damn, Paul Gilbert is good at vibrato with his index finger!!!", I starting just doing:
G:-4~
With every finger. Vibrato with 3rd, then 2nd, then 1st, then 4th. Since 3rd finger is usually most people's strongest finger for it, then the aim is to make the vibrato played with other fingers sound the same as the 3rd. If you do it for about 15mins a day, you'll improve rather quickly.
Then stuff like:
G----------9----------------9----------------9~~~~~~~---
D-9-10-12---12-10-9-10-12---12-10-9-10-12-----------------
Doing it as wide as I could!! Just to get the strength.
In a rare PG vid, he plays a part from Far Beyond The Sun and it sounds siiiiiick because of the vibrato, it's this section, and it's good practice:
e-----------------------|--------------------------------|----------17-16-17--21-20-21~~~---
b-----------------------|--------------------------------|19-18-19-----------------------------
g----------------6-5-6-|-11-10-11--14-13-14--18-17-18-|--------------------------------------
d-4-3-4--7-6-7---------|--------------------------------|--------------------------------------
a-----------------------|--------------------------------|--------------------------------------
e-----------------------|--------------------------------|--------------------------------------
I'll take this too kind sir, thanks!