base64_encode, forward slashes and mod_rewrite

[Dan Rossi <php@xxxxxxxxxxxxxxxx>]

Continueing on my prior problem, Ive discovered that base64_encode adds 
forward slashes in its encoded string, when its urlencoded it becomes 
something like

/feeds/UmFuZG9tSVZd%2FMChU7sMQqdUi%2FrgYHD7


mod_rewrite doesnt seem to like the %2F in the string and fails with a 
404 as it doesnt get a match using

RewriteRule ^feeds/(.*)$ /refer.php?$1 [L,NE]

What should i do ? Should i replace the / with a different character 
then convert it back later ?