Pretty much all of the ColdFusion language has been made available in some form using the cfscript syntax in ColdFusion 9. One item that I have not be able to find, though, is whether or not there is a script equivalent to the cflogin tag.
If there isn't, is there maybe a workaround using flash remoting gateway?
<cflogin>
in script style is not supported, but you can write your own.
For all supported tags in CF9 script, see: Extending ColdFusion Pages with CFML Scripting - What is supported in CFScript