Default [Q] How to adopt/take-in other rom's features?

Heya fellow xda's

We all knew that SlimKat Rom has very cool recents menu called "Slim Recents!". As far as I know, they say that it's not an app rather it is the outcome of 3000+ lines of coding.. I have seen many other roms that offer/built-in have 3 styles of recents menu.. the stock one, omni rom's recents menu and the slimkat recents.. Can anybody tell me, from which part of the slimkat's source code will i get that slim recents code or to put it simply, how to adopt that slim recents menu to my custom rom like the other developers did with their roms?
I'll be waiting to hear from you!
-The fellow xda