1) Make sure lsws is shutdown and the lsws logs direction is empty.
2) cd /yourlswsinstall/logs/
3) ../fcgi-bin/lsphp -v
4) Now check that the /logs/ directory doesn't contain any error logs from php complaining about errors loading modules.
5) verify that mssql.so is loaded by running ../fcgi-bin/lsphp -i
Note the .so extensions must be php version exact. If your mssql.so is compiled for mysql 4.3.9 and lsws is running php 4.3.8 or anything different, the .so will not load correctly.