one of the documented procedures in this installation of the ACS
ad_style_user_preferences_from_db   user_id
What it does:
Returns a list of prefer_text_only_p and language_preference from the users_preferences table; probably you should call this within a util_memoize so that you aren't kicking the stuffing out of Oracle.
Defined in: /web/philip/tcl/ad-style.tcl

Source code:

    set db [ns_db gethandle subquery]
    set selection [ns_db 0or1row $db "select prefer_text_only_p, language_preference from users_preferences where user_id = $user_id"]
    if { $selection != "" } {
	set result_list [list $prefer_text_only_p $language_preference]
    } else {
	set result_list [list "" ""]
    ns_db releasehandle $db
    return $result_list