libCurl can be downloaded at this page: libcurl class for Visual FoxPro 9
http://www.ctl32.com/libcurl.asp
the zip:http://www.ctl32.com/files/libcurl.zip
Read the explanations ...

copy the twiliox.prg in the main folder (libcurl), uncomment the lines as explained above and run.
it starts but i cannot try for account reasons -the message returned was:
SendFailed The requested resource /2010-04-01/Accounts/YourAccount/Messages was not found
In principe the code work...to try with your accounts.