Quite simply:
You need a CFW to run eboots.
You also need a pandora battery to install a CFW.
There are two options for pandoras:
#1 Buy one.
#2 Make one.
On the slim you have two methods of which to make a pandora. I will PM you links.
If you don't like the info I give you, you'll have to buy a pandora.
If you don't wanna buy one... You're screwed, as there aren't ANY more options.
@Ace: Don't answer questions with rhetorical questions.