Why would you want a PURL for an email? All email links are wrapped and tracked, unless you set mktNoTrack.
If you are saying you have a coupon code or something, then you could append that to the URL using a parameter token as you suggested. Just upload the two columns: Email | Coupon Code and it will work.
Totally agree with Josh. It doesn't make sense to generate pURLs (I think you're not really talking about Marketo pURLs, which are their own beast, but something like Bitly URLs) because the "short" URL will simply be rewritten to a longer tracking URL by Marketo.
So you'd end up with click.example.com/938f8fs723hsc763 -> bit.ly/23jwu -> pages.example.com/mypage.html, which doesn't offer any cosmetic advantages (it might offer specific tracking advantages if you like Bitly, but that's a totally different matter).
It also seems like from your next-to-last sentence you just want <a href="http://pages.example.com/mypage.html">click here</a> which is of course a standard link.
Thank you so much. This was really helpful! I think what we'll do is stick with the column upload to custom object. I tested it and it worked.