Adapted from HyperSprite's post:

Launching applications from ANY skin/screen in RR:

Skin commands.txt in your RR folder is your friend and new bible while you work on skins.

If you just want to play with an app in a skin and are not much of a graphics guy you could do this:

Recommendation: Go to your default skin directory and make a copy of it, do all you work and testing in this copy so if you mess it up you can just get the original files from the original skin dir.

Copy and paste the files generic_down.jpg, generic_empty.jpg, generic_off.jpg and generic_on.jpg files back into your skins directory. It should call them "copy of generic_down.jpg" etc.

Now, RENAME them to "appsname"_down.jpg etc... to whatever name you want to give your new skin. "appsname" would be your applications name and do not use the quotes. For instance mozilla.skin would be a fine name for that web browsers skin if in fact that is what you are making. For the rest of this document, any place you see "appsname" it should be replaced with whatever it is that you are calling your application.

Now, make a new txt file called "appsname".skin and fill it with the following text:

Start here>>>>>

MEDIACAR Skin
MEDIACAR "appsname" skin
"appsname"_empty.jpg,"appsname"_OFF.jpg,"appsname" _ON.jpg,"appsname"_down.jpg

/, B, x, y, w, h, Command;COMMANDCODES, Tooltip
B01,694,000,044,054,"CLOSE","Close"
B02,747,000,044,054,"EXIT","Exit"

/, L, x, y, w, h, color R;RGB, G, B, font size;FONT, font name, Code;LABELCODES, Tooltip;LABELALIGNMENT
L01,010,005,150,030,255,255,255,15,"Arial Narrow:B","TIME","Time"
L02,010,030,150,030,255,255,255,15,"Arial Narrow:B","DATE","Date"
L03,230,010,450,070,255,245,000,22,"Tahoma:B","TRA CKNAME","scroll-center"
L11,142,005,200,030,255,255,255,15,"Arial Narrow:B","=Car:",""
L12,110,030,200,030,255,255,255,15,"Arial Narrow:B","=Outside:",""
L13,180,005,200,030,128,255,128,15,"Arial Narrow:B","TEMP1",""
L14,180,030,200,030,128,255,128,15,"Arial Narrow:B","TEMP2",""

/, A, x, y, w, h, color;RGB
A01,000,055,800,545,000,000,000,"appsname"

END

<<<<<<<<end here

This little bit of code will get you the basic parameters to have the standard information in the top bar, an close and exit button and a application window you can fill.

Note: Make sure the file name ends with .skin and not .skin.txt (as windows will try to save it). You may have to disable "hide known extensions" on windows' folder options before you can see the real file name.

Take a look at this FAQ:
How to embbed any Application in RR ?

Basically, you want to get the apps name, like for instance if you are viewing this with internet explorer it might read "MP3Car.com Forums - new **app help** - Microsoft Internet Explorer"

As I just recently learned, "- Microsoft Internet Explorer" is probably all you would need (Partial matches work, but be carefull not to be too generic or you'll likely embbed the wrong window). So for example, lets say your appsname is "- App Name 2.1"

Now open your menu.skin file and look through the code for a button you want to activate your new skin, how about the TV button, find:

B14,010,415,135,110,"TV","Tv"

change the ending to this instead:

B14,010,415,135,110,"LOAD;appsname.SKIN;appsname;C :\Program Files\appsdir\appsname.exe;App Name 2.1","appsname"

Save your files and see what happens. Really all this is going to do is load your app into a window like Launch but off the main menu, if you want to add buttons and whatnot to do things to it, there is more to do. It may not work on the first try, but this should be a good starting point. There's also an open source skin editor at Road Runner's download page you can use to edit the buttons and labels on your skin.

Chris. (Thanks!)