Using available AMI-ID from Mifos X Wikipedia: http://en.wikipedia.org/wiki/Mifos_X with respect to the available versions. 

Provide your Amazon AWS credentials and login. If you are a new user, create the user first, go back to the Mifos X Wikipedia page & then click on AMI-ID. 

You are automatically brought to Step 2 on the wizard, by default a 'Micro instances’ is selected, you may need to select a 'General Purpose' family with type ‘m1.small’ as the t1.micro's memory is right on the edge of what’s needed to support MySQL, Tomcat 7 + Mifos Platform. 

Use default settings for steps 3 to 5 until you reach step 6 configure security group. 

If your first time using AWS you should use –Create a new security group option and add the following 'rules' to the security group: 

SSH (PORT 22), MYSQL (3306), HTTPS (443), Custom TCP Rule (8443) all with a 'Source' value of 'Anywhere' 

You will be asked to use a 'Key pair' which you will need to SSH onto the new instance, if this is your first time create a new key pair, be sure to download it and store in place as you will need it later, otherwise use an existing key pair. 

Then Click on Launch Instances. 

>> Click on Elastic IPs 

>> Click on Allocate New Address

>> Click on Yes, Allocate  

>> Click on Associate Address

>> Provide Instance Id & Click on Associate 

To access your instance through putty, follow below mentioned steps:- 

Using Putty key Generator to generate private key. Follow the flow as mentioned in the below images.  

1)       Click on Load to select Downloaded mifosxkey.pem                  2) Select All Files to display .pem (Public) key.

3)       Select mifoskey.pem & open                                                          4) Click on OK button

5)       Click on Yes button to save                                                            6) Provide destination path & name then

Use putty to run & verify, that the server & key are working using .ppk (Private) key.