How to change R file in stats?

Dear
I have changed some code in R file inside the stats package (dendrogram.R). Now I wan to test and run the stats package with the new updated code, what should I do in detail?

For testing the simplest thing you can do is to ?source the file in
your session. But R-core is very well maintained, why
would you need to change the core code? It will only bring you
maintenance chaos. If you need additional feature, maybe
you can have a look on CRAN if it is implemented.

Best,
-m