I'm working on updating this mod as I personally don't like how lazy, or incompetent, I was when I made it. The changes can be found below:
+Flynn now uses the new radio sound instead of the UT2k4 one, alongside his volume sounding somewhat closer to the other marines.

+Some voice lines did not play due to an incorrect sample rate. This has been solved!

+Although his voice lines are still repetitive, I've attempted to space them out a bit more. However, some voice lines *always* signify something. For example, "BUGS!" always means that there are parasites, instead of being a catchall watchout, shieldbug, and parasite voiceline.

+All of his sentry gun lines are being used instead of repeating a few.

+A few remaining Vegas lines have been replaced, completing all the replaceable dialogue with the exception of sealing doors, calling for other characters, and a few others that I just couldn't make any available voicelines make sense when replacing them, even if I spliced dialogue.

+Added a light around his portrait when the player hovers over him in the lobby, like the rest of the marines

+Some of the voicelines now make more sense when other marines talk to him. Some are even humorous, such as Sarge's dialogue with him about synup cola.

+Flynn now calls out dead marines, unlike before.

+Added UT2k4 male mercenary voice for his pain and death sounds.

-I tried to change the subtitles to show Flynn instead of Vegas but never figured out how. It still shows the original one when in-game.