Enrolment

Hi, there.
I've got two basic problems trying to set up an experimental moodle on my site. I'd like to check participatnts against an extermyl mysql database which has:
1. usernames with nonstandard caharacters (capitals, aso)
2. passwords hashed not in md5 but in SHA-1;

First problem could be tackeled by adjusting moodle settings (there is an option alowing non-standard chars in username), but the second one - i suspect - demands some tinkernig wit the code.

Can anyone tell me, where the function for MD5 hashing is located in the moodle code. By adjusting php functions from md5 to sha-1 ia might be able to battle this problem. Thanks;
O. Mar