Intercession

Here are some verses which appear to explain your concern about intercession as mentioned in Ayat-ul-Kursi and the verse preceeding that. It seems that our selves (nafs) will not be able to intercede or invoke intercession. However, there are angels in Heaven whom Allah will allow to intercede on behalf of those whom He wishes to grant intercession. Since we humans cannot invoke angels, hence it is beyond our power to seek intercession. We can only try to keep our duty, and hope that our errors and sins will be pardoned. Please see the following verses (I've pasted the translations, but you will have to check up the Arabic yourself):  

2:48 And fear a Day when no soul will suffice for another soul at all, nor will intercession be accepted from it, nor will compensation be taken from it, nor will they be aided.

39:44 Say, "To Allah belongs [the right to allow] intercession entirely. To Him belongs the dominion of the heavens and the earth. Then to Him you will be returned.” 

43:86 And those they invoke besides Him do not possess [power of] intercession; but only those who testify to the truth [can benefit], and they know. 

53:26 And how many angels there are in the heavens whose intercession will not avail at all except [only] after Allah has permitted [it] to whom He wills and approves. 

74:48 So there will not benefit them the intercession of [any] intercessors. 

You may also want to check out the intercession mentioned in the various places in the Quran by following this link: http://corpus.quran.com/search.jsp?q=intercession 

Please see Surah Taha, verses 109-114 for confirmation of the intercession mentioned in ayat-ul-kursi. 

[Quran 20: 108-114, Translator: Yusuf Ali] 

108 On that Day will they follow the Caller (straight): no crookedness (can they show) him: all sounds shall humble themselves in the Presence of (Allah) Most Gracious: nothing shalt thou hear but the tramp of their feet (as they march). 

109 On that Day shall no intercession avail except for those for whom permission has been granted by (Allah) Most Gracious and whose word is acceptable to Him.

110 He knows what (appears to His creatures as) before or after or behind them: but they shall not compass it with their knowledge.

111 (All) faces shall be humbled before (Him) - the Living, the Self-Subsisting, Eternal: hopeless indeed will be the man that carries iniquity (on his back).

112 But he who works deeds of righteousness, and has faith, will have no fear of harm nor of any curtailment (of what is his due). 

113 Thus have We sent this down - an arabic Qur'an - and explained therein in detail some of the warnings, in order that they may fear Allah, or that it may cause their remembrance (of Him)  

114 High above all is Allah, the King, the Truth! Be not in haste with the Qur'an before its revelation to thee is completed, but say, "O my Lord! advance me in knowledge."