1) determine what type of harddrive interface that needs to be slaved...ie...SATA ? or IEDE ?
2)purchase an external harddrive case that is USB 2.0 and self powered as well. The cases are reasonably cheap and can later be used as an external storage and back-up...which by -the-way had you been doing, this problem would not be an issue now!
3) by just connecting the USB external case with drive installed is all that you would need to do to "slave" the drive.
4) create the folder if you do not have a clean partition that is big enough.
5)install the recovery program...point it to the USB external drive to recover the lost data from.......point it to the folder for the recovered data to be stored.
6) Stop any screen saver programs or hybernation for the laptop and make sure it has the power adapter instead of battery.
7) let the computer run as it will take quite a while for the program to do its job...possibly up to 2 or 3 days or even more depending on speed of computer and the size of the drive

Here is an idea( not a recomendation make that choice on your own)) for a external case...note the screen shots showing the power adapter and usb cables and software for installing it.

Newegg.com - Galaxy METAL GEAR 3506UAS-BLACK 3.5" Black USB 2.0 External Enclosure - External Enclosures

Notice the size listing in the Title..... 3.5 .... this represents the case size will support a regular sized drive.... 2.5 ....is for laptop drives only.

This case is also only for a SATA interface.

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If you have an IEDE/IDE interfaced harddrive you might opt for a 5.25 enclosure....this would allow you to either use a harddrive or use an CD/DVD ...which is kind of neat if your laptops CD/DVD drive goes out on you!