There's a TSIB for it and doing a search within the forums should allow you to find the PDF of it. Try here http://www.clublexus.com/forums/is-2...ld-up-csp.html
I would suggest getting an oil catch can to prevent future buildup.
I ordered mine from http://www.rr-racing.com/Lexus-Air-O...isfaos0001.htm
I will create a thread once I install mine on how to install it in the IS250 and what not since it is designed for the ISF. If you want something 100% plug and play you could go with http://www.tokensolutions.net/lexus-...h-can/#reviews
There are plenty on eBay and Amazon as well that will do the job.
As far as a fuel additive, I use seafoam or Lucas about once an oil change. Techron is usually pretty expensive but I've heard a lot of good things about it.