You may install our apps via Cydia on a Jailbroken iPhone:
1. Open Cydia on the iPhone, click Search
2. Type the name of app
3. Click Install
If you do not already have Cydia on your iPhone, you will need to jaibreak your iPhone This will allow 3rd party software to run on your iPhone that does not meet Apple's SDK's terms.
Note: You can easily "unjailbreak" your iPhone by restoring your iPhone in iTunes.