You can have RR always launch the same GPS application or you can make it show a menu for you to choose which GPS application to use. This options you can choose by doing the following:

-Run RRconfig
-Scroll Down to the GPS section
-Choose the GPS mode to "Menu" (or preferred GPS)

To Setup Your GPS:

Map Monkey

-Set MapMonkey's Path
-Set OverSpeed Indicator limit (Optional)

For IMPROVED Map Monkey Support

-Run Map Monkey Config and turn Advanced GPS ON -- If you don't do this, the Speed information will not work in RR's skins.
-I recommend setting MM to start with a set position of 0,0 and size of 800x600 (or your screen size) -- to prevent embbeding issues.
-Open Settings.INI from Map Monkey's install location
-Locate and make the following changes to this section:

[Plugins]
//Allow custom apps to interact with the frontend?
Enabled=Yes
ListenPort=9913

MapPoint

-Set the GPS option to "Mappoint" or "Menu".
-Specify if you use Mappoint North America or Europe
-Specify your GPS Serial port -- your GPS MUST be set for NMEA
-Specify the default Coutry/City for searching locations (optional)
-Make sure Mappoint is propperly setup and that the types of locations you'd like to search for are selected in Mappoint (for the nearby feature).

Note: Streets & Trips is NOT meant to be interfaced with any application (including RR), but if that's what you want to use, take a look HERE.

Other GPS Applications (i.e. FreeDrive)

-Set the External GPS path to your applications path
-Set the GPS Window Name to your GPS Window name

If your GPS application needs specific parameters, you should add a " " (including quotes) after the application's path. For Example (for External GPS Path setting):

C:\MyGPS\MyGPS.EXE" "Param1 -Param2 Param3

You can look at THIS FAQ to find the GPS Windown Name for your GPS application.

For example, for FreeDrive you should enter "FreeDrive" (no quotes on the GPS Window Name).