Not much I can do to help, but as a person who tried once to make the mod (and the last time sadly), I guess I can comment on the problems that may happen.

(The Dude Himself)

• The Dude actually has little to none "follow me" lines in the base Postal 2 and Apoc. Weekend. I know that Paradise Lost has some when the Dude is calling out for Uncle Dave over the radio, but no one has extracted the lines yet (at least to my knowledge).
  
• The Dude has varying audio levels judging from his audio files. You may want to amp some of them up so it doesn't get drowned out by other PD2 sounds (although if the base audio levels are fine, then I guess it's okay).
  
• Callouts are going to be something, but you can just make something up, leave in Bohdi's lines, or just use a blank soundfile.
  

(The Sound Modding)

• There are likely going to be "unreplaceable" .stream files. These are .ogg lines converted to .stream as opposed to the .wav files converted to .stream. Luckily since Bohdi has a specific sound folder for him, you can either leave them in or do what Microsoft Jacket does and use a blank .stream file (btw, .ogg -> .wav -> .stream conversion only makes a blank line in-game).
  
• Unreplaceable lines include: "Control Phase: Special Unit Callouts (not Assault Phase)", "Medic Bag Plz Lines (although this may not apply since Jacket's release), "Ammo Bag Plz Lines (Same as previous), alongside some more I think.
  
• (Usually I keep a backup of a previous update character's lines so I can Copy -> Paste into a "new update" Bohdi folder -> Replace Files -> [and once the old files are still HIGHLIGHTED in the new update's "Bohdi" folder] Move back the old lines into some folder. This isolates the new lines if Bohdi ever gets "Sydney" lines).
  
• Same can be done to isolate .ogg (.stream) lines if you reconvert the .wav lines in a different folder and move them back into Bohdi's Folder. And while they are still highlighted, move them into a different folder to isolate the .ogg (.stream) lines so you can replace them with a blank .stream file.
  
• Your lines can be however long you want (since this isn't a music mod).
  
• Don't forget the mission_gen folder since that may have Bohdi lines in there as well.
  
• Don't forget mod_overrides doesn't support .stream files that end w/ "*insertnumbershere*.1.stream", instead, use "*insertnumbershere*.stream"
  

(Other tips or something)

• Idk, but here are some silly lines from the voice actor himself on his youtube channel: https://www.youtube.com/user/RickHunter811/videos
  
• If you need a archive of lines from in-game Postal 2 and Apoc. Weekend since extracting them from Unreal Editor is tedious, https://www.dropbox.com/s/n24ljgcpqco3syl/Postal%20Dude%20Voice%20Lines%20%28from%20P2%20and%20AW%29.zip?dl=0 (You'll have to get the new Paradise Lost lines somewhere else though since I don't have the expansion).
  
• I had a concept for how he would announce "*insert special unit* down!" that would emulate the style he says in Postal 2 by having him say an after message to spice things up (example: "*special unit* down! And another one bites the dust" or "*special unit* down! One for Lil' Johnny". Idk, many lines can be experimented with with how Postal 2 lines work.
  
• LASTLY:
  
  

Sorry for the wall of text, but I guess this is what tips I have for this really. I also made this a while back, but since I got lazy and busy.... http://i.imgur.com/FVmTaAW.jpg

- W.R. :dosh: :yeehaw: