I think now php can be upgraded to version 5, so php5-cgi is more or less deprecated. There's no tweaks for php5 to work on SME7, just upgrade it from centosplus repository. Of course, it's not recommended to do so, you should:
- test it first on some test server
- be sure to know what you're doing, so you can reverse if things goes bad
I've upgraded php on two production server and for now, everything is fine.