Well, There is currently two guides regarding Wesker and Jill's fight

http://www.speedrun.com/re5/guide/3gvuc http://www.speedrun.com/re5/guide/304li

It's possible on different difficulties It's a bit inconsistent, but it's certainly possible.

I also have questions regarding if some glitches are legal? As well as the oil field skip?

Oh, apology I missed the small remark about it being done with Sheva, I'm happy to say we have a new runner that is currently trying to run only as Sheva, http://www.speedrun.com/run/zxv2p88y

I'm sure he'd be happy to research with you any strategies of using her for the speedrun. Do consider watching his run,

thank you i will watch it

If you're talking about the Jill part of it then yes, either character can do that, the set up will just be different. In my co-op runs Auddy (Sheva) is the one shooting Jill.

I think we're talking solo here so as far as the Wesker part I wouldn't know about that.

Yeah I watched your run before not recent though but it was interesting... I speedrun this game more than re4, becuase i have it for X360, and re4 for wii so i dont play re4 much

The quick Wesker can only be done by host. Who you pick doesn't matter.

I was gonna mention that Snow but I assumed the question was geared toward solo