After searching all over these forums and all over the net and being unable to find a clear tutorial on how to play Gameboy Color games on the LG Voyager, I decided to do some experimenting of my own and figured out a simple way of making it work. I'm totally new to these forums so I thought I'd introduce myself with something helpful!
First of all, you will need a Java-enabled LG Voyager. Correct me if I'm wrong, but I believe that the Canadian version of the Voyager is the only Java-enabled one (US versions use BREW). So unless there is a way for you to run Java based applications on your BREW-enabled phone, this trick will not work for you. However, it is good news to my fellow Canadian Voyager owners!
Alright, to begin, an application called Meboy is what is used to play these games. In order to save you the hassle of downloading the Meboybuilder and finding a correct ROMs, I have included a pre-built Meboy file which includes every single Pokemon game on the Gameboy Color (Blue, Red, Yellow, Gold, Silver, Crystal).
Here's what you have to do:
1: Download the Meboy jar file which includes all the pokemon games from here http://www.megaupload.com/?d=0BJY41OS
and save it somewhere you'll remember.
2: Head here http://rumkin.com/tools/sprint/
and under the "Upload games, applications, Java Midlets" browse to where you saved the Meboy file, then right below the "Browse" option there is a "Folder" option. Select "Games" for this.
3: Leave the "Send To" field blank and click "Upload Midlet". Be patient, this takes about a minute.
4: You will now have a page with a Jump Code. Go on your LG Voyager's mobile browser (the stock one and NOT Opera Mini, as I am not sure if it works correctly with it). Follow the instructions and head to the URL listed on that page. You will be prompted to enter the Jump Code, do so.
5: A message will come up asking you if you want to install the application to your games folder, accept it.
6: After a few moments, the game will be installed on your phone. Head over to Entertainment --> Downloads --> Games --> MeBoy and run it.
7: Before starting a new game, I recommend going under Settings and checking all the boxes under Scaling (Scale to fit, Keep proportions, Start in full screen) because the default screen is quite small and hard to see.
The game runs at a solid 10-11 FPS, which is quite smooth for a GBC game. I hope this works for all of you and post any question in you're unsure about it.
By the way: you can use Google to download the ROMs you want, but remember that you will need Meboybuilder 1.6 (just google Meboy and you'll find it) and make sure the ROMs you download end in .gbc. Just add those to Meboybuilder and it will create a new .jar file with your ROMs compiled. Then just repeat the same process to add them on your phone as I listed above.
EDIT: And in case the megaupload link does not work for you, I've attached the file below.