there are many way in which you can install application on mobile phone ....

Infrared and Bluetooth.

IR or Bluetooth technology can be used to send the MIDlet from a PC to another device .And these two technologies can also be used to send JAR files between two devices.Of course,the file must be saved in source device memory by any way before sent.And the destination device must support installing applications via MMS.

serial cable installing.

device has a serial cable port and connectivity software (either Nokia PC suite or the Ovi Suite) for a PC, the MIDlet can be installed on the device over a serial cable. To install the MIDlet, double-click on either the *.jar or *.jad file and follow on-screen instructions. On a PC, if jar/jad files are not associated with PC suite or Ovi suite by default, you can right click and select "open with" then choose "Ovi suite" or "PC suite" as applicable.

nother way to transfer the MIDlet to the phone is store it (JAR and or JAD file) on a Web server and download the files using the browser of the phone (so called OTA download). Note that the server has to have the MIME types correctly defined.