No, this construction is impossible because it involves nominal syntax (*hoc domūs tēctum*), while the gerund has verbal syntax (**in hōc scrībendō*) and governs the same case as the verb (**epistolārum scrībere*). With verbs [that govern the genitive][1], in which it expresses the stimulus that evokes some feeling (memory, pity, incrimination), you can say:
- *eōs **prūdentiae** monēmus* > *tempus perdimus eōs **prūdentiae** monendō*.

 Other than that, such syntax is probably impossible even in Late Latin, where *hoc epistolārum scrībere* "this writing of letters" becomes grammatical. That said, due to the suppletive relationship<sup>**1**</sup> between the infinitive and the gerund, it wouldn't surprise me to find a substantive-like *prepositional* use, eg. **in epistolārum scrībendō* in Late/Medieval Latin.

**1**: the infinitive serves as the nominative of the gerund.

In the Cicero quote, **operae** is indeed the object of **pōnere**: 'to put in **some work.**' The grammar becomes more apparent if you add an explicit pronoun: ***(nescio/ali)quid** operae.*


  [1]: http://dcc.dickinson.edu/grammar/latin/genitive-verbs