request for ideas?

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If this insn't allowed, please delete.

Basically I found this jacket at a thrift store the other day that I plan on using as part of Halloween costume (Daria). It is the right size, shape, style, etc except the color is just ever so off.
It's 100% cotton (almost like a twill?) and is an olive drab color.
What I need it to be is more like a grassy green.

How might I go about doing this?
I've been to what very limited shops we have here in my small town and the only fabric dye anyone has in green is Rit's DARK green.

Any suggestions?
And thanks in advance!