Have you considered wrapping your Java application in an .exe using launch4j? By doing this you can embed a manifest file that allows you to specify the "execution level" for your executable. In other words, you control the privileges that should be granted to your running application, effectively telling the OS to "Run as adminstrator" without requiring the user to manually do so.
For example...
build.xml:
<target name="wraprispacs" depends="rispacs.jar">
<launch4j configFile="myappConfig.xml" />
</target>
myappConfig.xml:
<launch4jConfig>
<dontWrapJar>false</dontWrapJar>
<headerType>gui</headerType>
<jar>bin\myapp.jar</jar>
<outfile>bin\myapp.exe</outfile>
<priority>normal</priority>
<downloadUrl>http://java.com/download</downloadUrl>
<customProcName>true</customProcName>
<stayAlive>false</stayAlive>
<manifest>myapp.manifest</manifest>
<jre>
<path></path>
<minVersion>1.5.0</minVersion>
<maxVersion></maxVersion>
<jdkPreference>preferJre</jdkPreference>
</jre>
</launch4jConfig>
myapp.manifest:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
<security>
<requestedPrivileges>
<requestedExecutionLevel level="highestAvailable"
uiAccess="False" />
</requestedPrivileges>
</security>
</trustInfo>
</assembly>
See http://msdn.microsoft.com/en-us/library/bb756929.aspx and the launch4j website for mode details.