alternative OWA / OMA addresses

Rather no. Sofware is writen in that way that it call files from /exweb folders.
I handle with similar reqest with workaround like that way: https://www.experts-exchange.com/questions/23495000/How-to-change-http-server-exchange-to-http-server.html 

Yes, you can create two alternate sites and then set them to redirect to the /exchange or /oma parts of your site.
That's the easiest way.

There are more elegant solutions in Ex12 but that doesn't have OMA so is useless to you.

simonpainter could you give me a walkthrough on creating two alternate sites

http://support.microsoft.com/kb/308163
Basically the default site listens for any HTTP requests on 80 and responds with the relevant page regardless of the domain. What you need to do is create two more virtual sites which both listen on 80 as well but pick up specific domains in the request header. IIS then passes the request to the relevant virtual site so owa. goes to one site, oma. goes to the other site and everything else (including mail.) goes to the default site. Then point cnames for oma. and owa. to mail. and you should be ready to rock.

This might help for information: http://support.microsoft.com/kb/816576

u reached out. thank you.
next question: what format should the host header be: can it be mobile.domain.com


So far I created a new at port 80 ALl ALl unassigned IP"s and pointed to OMA directory

There are three bits of information that you can set to determine which virtual server the requests are forwarded to.
Port - not applicable here as we want it all on port 80
IP - unless you have public IP address space coming out of your ears it's probably best to keep to using one IP
Host header - this is the bit you need to vary.
If you don't vary at least one of these then IIS will stop and refuse to start because it doesn't know which virtual server to send the stuff to. In your scenario you want to create two virtual sites, both on all unassigned IPs and both on port 80 and then go into the advanced settings for them and call them owa.yourdomain.com and oma.yourdomain.com

They can really be anything.yourdomain.com and you could have several aliases for the same site if you want although that just adds to user confusion. You also need to remember to set up the correct DNS records as well though.

I set up the host headers and the dns

now for the next question

when browsing to owa.domain.com or oma.domain.com i see a list of files that are there.  like a directory listing.
do I need to enable something else for it to execute the script.

you will need to ensure that your redirect is called default.htm

Or you can use IIS to do the redirect
http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/6b855a7a-0884-4508-ba95-079f38c77017.mspx?mfr=true

should I use directory or url like http://domain.com/oma http://domain.com/owa

the url redirection doesnt seem to work, neither does dir.

a better question would be what paths should i use for oma and owa. i used the ones i got off the properties under default web site

depends what you have set up to work. As exchange in on the default site it will not be fussy about what header it accepts so as long as there is a corresponding DNS record (mail.yourdomain.com for example) then it will work. Have you set up ssl on the default site? What name do you have the cert under?

i dont have ssl no. thats a different task. maybe the one following this one.

here are some screenies of dir setup
mobile.JPG
owa.JPG

superb