I may have the option of starting a part-time master's degree in computer science... Would this help even without an undergrad?
If you work for a subsidiary of a US company outside of the US for at least one year then you can transfer on the L-1 visa to their US office. Just be aware that you can't switch companies like you could on an H-1B. However, L-1 visa holders can still apply for a green card. Once you have that you're free to change employers.
One technicality: If you work for a big company (like Google) then you're basically guaranteed to get the L-1 after one year since those companies typically hold the so called L-1 blanket. Otherwise it's a more involved process where you might get rejected.
I have friends who are currently on an L-1 in SF through big companies (= L-1 blanket holders) and getting it was basically a formality.
The L-1 also has the advantage that there is no annual cap like there is on the H-1B. You get it or you don't. No lottery. One big startup that I interviewed with opened up an office in Vancouver specifically for H-1B rejects to get them to their main office in SF through the L-1 one year later.
More information on Wikipedia: http://en.wikipedia.org/wiki/L-1_visa
Various states who have launched or are considering launching have different requirements. CO does require either an undergrad or masters' degree, so work experience wouldn't count. MA is Masters' only.
Keep in mind that the H-1B itself does offer work equivalency, but it's 3 years work experience → 1 year of academic training, which means that 5+ years is unlikely to meet the USCIS test requirements.
I don't have a degree or a diploma.
If you are going to start a masters for this specific reason I would strongly recommend you get confirmation that the degree you're going for qualifies.
You'll also need a US company to sponsor your visa application.
The problem is in trying to prove the "Bachelors equivalent". I personally know a friend from Bangladesh who did that successfully by using a good lawyer/law firm.