Oh, I thought it was an attempt to stop yourself changing nicks repeatedly, writing a script to counter SVSNICK is pointless, since they can jus keep doing it and you'll flood off.
Find another network that has people with common sense..
However, if you really want it.
alias nick { set -u5 %^nc $1 | !nick $1 }
On *:Nick:{
if (($nick == $me) && (!%^nc)) { nick $nick }
}
To test it if you dont have access to SVSNICK;
/nick testingnick1 - should be fine.
Wait 5 seconds, /!nick testingnick2 - should result in you changing to it and back to testingnick1.
Eamonn.