Updated 5:40 p.m. PST with more information on storage capacity.
Caching radio stations to listen to later is, as far as I'm concerned, Slacker for BlackBerry's No. 1 feature.
While sound quality and speed are excellent as long as you're on a Wi-Fi connection, as soon as you stumble into 3G territory, quality takes a noticeable nosedive. It still sounds good, mind you, but buffering bumps and delays take their toll. Even worse is when you're cut off completely from all data sources and you just have to have your Slacker Radio. My personal case in point: the underground train commute.
If you have the capability to use this crucial caching trick, so far unique to BlackBerry among the mobile cell platforms, you ought to do so. Here's how.
Step 0: Check the specifications
Make sure that your phone is running version 4.3 of RIM's operating system, if not higher. Also, make sure you have a microSD card. Otherwise, don't even bother.
Step 1: Get pickin'
When you begin playing a station, press the menu button, and select the second option, 'Cache Playing Station.' You can also cache an inactive station by highlighting it and selecting 'Cache Highlighted Station' from the context menu. I have room for 60 stations on my 8GB microSD Card.
(Note: Slacker told us they will institute a 15-station limit, though right now there's no cap. Hence my impractical, but nevertheless possible, capacity to store 60 stations. Roughly calculated, that's a 125MB minimum storage requirement per station. According to Slacker, "The limit is useful to avoid lengthy station refresh times and inadvertent use of the entire SD card for Slacker music.")
Step 2: Plug it in
Simply telling Slacker Radio to cache a station isn't as good as storing it--yet. To finish the job, stick a USB cord into the BlackBerry and connect it to your computer. Turn on Mass Storage Mode.
Step 3: Slacker's sync
No need to look for the BlackBerry Desktop Manager to pop up--but you might see a BlackBerry window pop up from which you can process files (this is the E-drive on my PC.) Ignore this. What you really want is the second pop-up window, the removable disk helper window (F-drive for me), which has an option to sync Slacker stations. Double-click the Slacker station loader and you're good to go. Note: Syncing can take a few minutes, especially the more stations you have.
Step 4: Cache payout
After syncing, your station roster should show the number of stations you've cached in parenthesis. When connectivity dies out, you can click in to this list to play your favorite artists' songs.
I didn't have any problems setting up the sync on my BlackBerry Bold, but not everyone has been so lucky. If the Removable Drive dialog box doesn't open and offer you the Slacker syncing tool, try doing it manually. Open the Removable Drive for your memory card from My Computer. Then double-click the Slacker executable file (slacker.synclauncher.exe) to get started.