I second jan Ote. Sometimes, but not always you can rephrase it to avoid dealing with the concept lexically. For example, adding "jan li tawa" will imply that the agent is still alive without specifically saying "to live"
If jan Sonja disappeared, and it was up to the community to carry on, I'd be more willing to follow an overload of an existing word than a new base word. e.g. li pan/to live. This sort of innovation, in my opinion is already happening.
If you have to use a loan word, then there is huge loophole, namely proper modifiers. lon Wita, (existence of the "living" sort") tawa Wita (motion of the "living sort"
Only proper modifiers are an open lexical category in toki pona. All other categories are closed, just like I can't invent a new English preposition or pronoun, although in english I'm free to verb a noun or coin a new noun or acronym.
I think the license on toki pona says, don't write a for-sale toki pona guide that competes with the book she's planning to write. The anarchist punk band Pischimo in Russia played a concert in Russia-- I presume tickets were sold--and jan Sonja said she thought that sort of usage was fine (IM conversation long, long ago). Speaking of the book, follow the wikipedia recent changes RSS feed-- at the moment it is the best measure of how much time Sonja is spending on toki pona-- http://en.tokipona.org/wiki/Special:RecentChanges
jan Sonja has a real job now and tends to only work on toki pona on weekend and late at night.
And please publish, preferably under the same or more liberal license than the one jan Sonja uses (creative commons)-- amateur linguists like myself need as much toki pona text in the corpus as possible for answering questions like, what usages has the community decided are legal, what usages are happening spontaneously, which rules are the community ignoring, etc.
The most official looking scrap of information says "pu" works like a comma. If this is true about commas, then "pu" is some sort of introduction to a clause. Commas have other uses (written symbols of a verbal pause, splitting enumerated items, etc-- but those are rather useless applications for a word) I have proposed that "pu" introduces a verb phrase that modifies a noun, in the same way that "pi" introduces a noun phrase that modifies a noun. jan Kipo doesn't like the idea at all-- so far the only other legal alternative I can think of is "pi tawa", as in jan moli= dead man (stative) jan pi tawa moli (killing, dying man). A "pu" solution would be jan pu moli- dying man, jan pu moli e jan (killing man).
There are other theories about what it means, posted elsewhere.