Those instructions in the manual are for windows. Oh well! Go to the menu bar & click on the Limewire name at top left & a menu will show. Select Preferences. This is where most OSX program preferences are found. Most of the options are identical to those of windows.
See the Upld & Downld options for no. of slots & bandwidth control for both of these. Depending on your internet speed you'll need to choose an appropriate setting. For me I select Modem even though I use broadband 256/64 kbps. For more about these speed settings see What speeds are T1/T3, etc. for LW

For general downlding skills, see the following link & follow all the off-shoot links to find hints & extra skills to help: To continue files downlding (click on link)

If you want to downld music then you'll probably want to enable iTunes auto importing, so check the iTunes options in the prefs about this. Don't forget to press the Apply button after making any changes. Oh ... & don't forget to look at the Stickys in this & other sections.