For RECEIVING mail an outlook.com alias is good enough. On the phone you just create the main account, go to folders, for each alias folder you tell it to sync that folder too and pin it on start screen. Make sure the alias folder is under the main account inbox (a subfolder or Inbox), because WP8 email client do not allow Not Syncing the Inbox.
The tricky part is for SENDING mail from an alias account. Oulook.com don't allow sending with an alias address, so your recipient will always see your main account address on the From address. Which defeats the purpose of an alias altogether. Hence an smtp service which will allow the From and/or Reply to field is from your alias account. Then you can create the aliases account on your phone, making sure you put the aliases sync as MANUAL (don't ever sync those inboxes, you only need the send part). Oh, you also lose the reply capability, since you have to make a NEW EMAIL to reply (to get the From and reply to fields as your aliases address). *sarcasm alert* Aren't MS aliases wonderful?
The easiest thing for outlook.com is create a separate account, don't use aliases. Spare the headaches.
Sent from my RM-885_apac_indonesia_217 using Tapatalk