I've had this done for a while and up on some other sites but, I thought with the new 2.5/2.6 downgrader we could use all the guides we could get so here's how to setup the PC to PSP file transfer feature.
1.) Download IR shell and install.
2.)Download the network host server for windows and place the file in the directory you would like to have access to via IR Shell.
3.) Launch IR Shell and run the configurator by by pressing R + start.
4.) Scroll down to NetHost IP Address and enter the IP of your machine which will usually end in with three numbers like ".101" not your routers IP which will usually end with a single number like ".1"
5.) You can find your ip address by going to START then RUN and type in "ipconfig" (with no quotes).
6.) You can also find it by going to START / CONTROL PANEL / NETWORK AND INTERNET CONNECTIONS / NETWORK CONNECTIOS / right click on LOCAL AREA CONNECTION / select STATUS / then click on the SUPPORT tab.
7.) Now press start and scroll down one option below and make sure the number reflects the connection you want to use from your network settings listed top too bottom.
8.) Save your settings and exit by pressing the O button.
9.) Now go too where you put the network server and execute netbios.exe
9.) A command prompt should stay up now, leave that open.
10.) Now go back to IR Shell and press L + analog down and it should initiate your connection.
11.) Press the square button until you see the root of your memory stick (it will have the IRSHELL & PSP folder). Go to the top of the page, select the two periods " . ." and hit X.
12.) Now you will see a menu with:
nethost0:/ - select this one
13.) Now you should see the directory of where you put the server files.
14.)You can now select eboots in the folder without the % and it will run on your PSP!