Remote Exchange users question

In my Win2K3/exchange 2k3 environment I use an internal domain name of corp.mycompany.com.  I have a registered domain name on the internet company.com and have a 3rd party hosted site and pop account.  I need to keep it this way since my IT resources are no where near where they need to be to manage the static IP, web server, pop server, ect.  My main goal for using Exchange is to have simplified backup of e-mail and a few other features.  The setup I have now is the internal users have an e-mail of user@corp.company.com, there real outside address is user@company.com.  I have a 3rd party pop3 connector that downloads messages every 2 minutes.  That works perfectly along with a connector that ships all e-mail out though my providers smtp server.  I know this is redundant but I have moble users not using the exchange server who still download directly through pop.  The only issue I am having is with remote exchange users.  RPC over HTTP sounds great but I need help.  I need a comprehensive tutorial on how to set this up.  Preferablly without having to use SSL or a certfiicate server but if I must I will.

Thanks in advance