Goal: Have unlimited talk time on my cell phone

How:
I have a cell phone with unlimited Incoming Cellular minutes and unlimited
WAP Internet access.
I also have a PC at home with a persistent connection to the internet,
access to a telephone line, conference call capabilities and a webserver.

What I want to be able to do is connect to my PC using my cell phone WAP
interface (webserver) and instruct it to establish a 3-way conference call
between my cell phone and some other number I specify.

Problem:
I know how to connect to my PC via WAP/webserver. I know how to specify a
number I want to call. What I can't figure out is how to write a program
that can control a modem to:

1) open the modem port and dial a number ATDT 9,222-555-1234
2) click the FLASH interface to establish the second number
3) dial my cell phone number ATDT 9,222-444-2323
4) click the FLASH interface again to connect the 2 parties
5) <wait until the calls drop OR some specified time>
6) disconnect the line

What would be the easiest way to do this? The preferable thing is if I could
do this via a command line interface tool. However, if I had to use a
library and write a program, I'm fine with that.