Here is a small tutorial by me.

Steps: 1-8

1: Extract USpeedPM-1-0-34.zip
2: Copy profileManager.prx which is in the seplugins folder to your own seplugins folder or if you don't have it just copy seplugins to the root of your memory stick.
3: Open up the PSP folder and then SAVEDATA.
4: Now copy USPM20110315 folder to your own PSP/SAVEDATA folder.
5: Now open up your own seplugins folder and if you don't have a vsh and game txt file make them ( right click New Text document )
6: Paste this ms0:/seplugins/profileManager.prx 1 into your vsh and game txt files (if you are on PSP GO paste this ef0:/seplugins/profileManager.prx 1)
7: Now to Customize your profile Go to your PSP/SAVEDATA folder and open up USPM20110315 folder and edit profile.infos using a txt editor.
8: Now to add a new profile open up your PSP folder and create a new folder called SAVEDATA_1 now copy USPM20110315 folder into your SAVEDATA_1 and repeat step 7 to Customize it.

Now you are finished restart your PSP... press UP & Left to bring up your profiles and press Right or Left trigger to switch between them. And if you want to terminate the Plugin press Right & Left trigger at the same time. (You can Now change the button combo by editing profile.infos)

You can repeat step 8/7 to add more profiles when ever you want. Just add a new folder in your PSP folder named SAVEDATA_2