I highly suggest that you
do not use SEO4SMF, the newest version or otherwise! It is not updated regularly and there are several recent and outstanding vulnerabilities that can lead to your site getting
hacked!
I found out about them from the following sites:
http://www.milw0rm.com/exploits/7723
(google translated from Spanish) http://translate.google.com/translate?prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fforo.elhacker.net%2Fbugs_y_exploits%2Ffalla_en_el_mod_seo4smf_para_smf-t241029.0.html&sl=es&tl=en&history_state0=
(original topic in Spanish) http://foro.elhacker.net/bugs_y_exploits/falla_en_el_mod_seo4smf_para_smf-t241029.0.html
The person who found this exploit patched their own forums (as stated in their post), but obviously only wants to provide the vulnerabilities so that hackers may exploit other SMF forums using SEO4SMF.
I HIGHLY RECOMMEND that you uninstall SEO4SMF until someone patches this and makes the patch publicly available.
This finding is recent, as of January 9th, 2009!
Note: I do not claim to be a PHP/MySQL developer or expert, so I cannot offer any support. However I do read Spanish, so...this is just my personal warning.