Research after the bachelor's degree has ended but before applying to Master's program Background: I'm planning to attend graduate school for CS at a school (UT Austin) where state residents pay significantly less tuition. Therefore, I will move to the city where the university is 16 months in advance of applying. I am planning on first applying to a Master's program to gain research experience and boost my credentials. 

I want to do research with a certain professor at this university before applying to the Master's program. 

Question: What can a non-enrolled student with only a bachelor's degree do to improve his/her chances of being able to do research with a professor to boost the student's resume for graduate admissions?

I.e., replicate his important research, try to publish in his area of research, use my university email so it's less likely to be treated as spam, have a professor I'm doing research with beforehand reach out (while continuing research with this professor), etc?

Edit: Well, I've been trying to get undergrad research as a distance learning student right now and I haven't gotten any response back yet. I wonder if it'll be even harder after I graduate.
Contact the professor and ask (politely!).

Nobody ever explained to me how you applied for a doctorate until after I found out my undergrad results and people started suggesting I should think about it, so I approached a few of the departmental lecturers whose work I liked, explained that I was interested in working with them and asked if there was any way I could get experience in their group. One of them turned out to have some short-term funding and paid for me to work with the group for a year as long as I did two days a week of general group jobs. During the year I was able to get to know the group, contribute to papers and apply for doctoral funding (which was successful).

So, from personal experience of being in a similar situation, it's worth asking. This took place in the UK about (ahem) 20 years ago, but unpaid or self-funded 'placements' are common in other countries too. Since you have a clear aim (a specific project or area that you want to strengthen your CV in, for a defined period) and it doesn't sound like there is a specific structure in place to facilitate this, then I'd give it a go.