Lookbehind/Lookahead Assertion with Npp Regex

Today I was looking for a way to get the last character of a pattern so that I could replace it. In this example, I wanted to find the last pipe in a record like 8|34346|. Normally with regex, one could do this using a lookbehind assertion. To do this with notepad++ you must utilize the implicit search buffer, by using a \1 in the replace field (for example, to access the first set in the buffer).

So by searching on: 1|10007|someemail@someplace.com|lastname,first name|X

"Find What:" ([0-9]*[|][0-9]*)[|]
"Replace With:" \1%

I could get: 1|10007%someemail@someplace.com|lastname,first name|X

BIG THANKS TO DEAN NAIRN!