First, download the appropriate for your BlackBerry device model spelling checker application itself through one of the links below:

LexSpell v. 2.7.421 for BlackBerry - designed to work on BlackBerry devices with keyboard (requires BlackBerry OS v. 4.2.1 or higher);
OR
LexSpell v. 2.7.47 for BlackBerry Storm - designed to work on BlackBerry devices with touch screen (requires BlackBerry OS v. 4.2.1 or higher);
OR
LexSpell v. 2.5 for BlackBerry - designed to work on older BlackBerry devices (requires BlackBerry OS v. 4.1.0 or higher)

Second, install the proofing database(s) you want:
Languages:

English (American)
English (British)
French (European)
German (Classic rules)
Italian
Spanish (European)
Portuguese (Brazilian)
Portuguese (European)