Here’s my translation

Alan

Slík orð sendi hann norður í Víðidal til Guðmundar mágs síns og þeirra
He sent such words (neut plural, ie the same message) north to Víðidalr to Guðmundr his son-in-law and to them

Ásgeirssona og það með að hann hafði lýst vígi Kjartans á hendur öllum
(the) sons of Ásgeirr and with that (ie in addition) that he had declared (the) slaying of Kjartan (to be) at the hands of all

mönnum þeim er í tilför höfðu verið nema Óspaki Ósvífurssyni. Hann var áður
those persons (men) who had been in (the) attack except for Óspakr Ósvífr’s-son. He was already

sekur um konu þá er Aldís hét. Hún var dóttir Hólmgöngu-Ljóts af
condemned-to-outlawry over that (þá = fem acc demonstr article) woman who was-called Aldís. She was (the) daughter of Dueller (lit: islet-walking)-Ljótr of

Ingjaldssandi. Þeirra son var Úlfur er síðan var stallari Haralds konungs Sigurðarsonar.
Ingjaldssandr. Their son was Úlfr who later-on was (the) marshall of King Haraldr Sigurðr’s-son.

Hann átti Jórunni Þorbergsdóttur. Þeirra son var Jón faðir
He married (had (as his wife)) Jórunn Þorberg’s-daughter. Their son was Jón, father

Erlends hímalda, föður Eysteins erkibiskups.
of Erlendr (the) flabby (according to MM/HP), father of Archbishop Eysteinn.

Ólafur hafði lýst vígsökinni til Þórsnessþings.
Ólafr had proclaimed (referred) the-slaying-suit (def art suffixed) to (the) Þórsness-Thing.

Hann lét flytja heim lík Kjartans og tjalda yfir því að þá var engi kirkja
He caused to convey home Kjartan’s body and raised-a-tent over (it) because then (ie at that time) (there) was no church

ger í Dölum. En er Ólafur spurði að Þorsteinn hafði skjótt við brugðið og
built (pp of göra) in Dalir (The Dales). But (And) when Ólafr heard that Þorsteinn had got going (sprung-into-action) at-once and

hafði tekið upp mikið fjölmenni og svo þeir Víðdælir þá lætur Ólafur safna
had brought-together (lit: taken up) a great crowd-of-people (men) and they (the) Víðdalers likewise (= svá),  then Ólafr causes (present indicative) to assemble

mönnum fyrir um alla Dali. Var það mikið fjölmenni.
men from across all Dalir (The Dales). That was a great crowd-of-persons (men)

Síðan sendi Ólafur lið það allt til Lauga og mælti svo: "Það er minn vilji
After-that Ólafr sent all that host to Laugar and spoke thus: “That is my wish

að þér verjið Bolla, ef hann þarf, eigi verr en þér fylgið mér því að
that you defend Bolli, if he is-in-need, no worse than (if) you should-help (present subjunctive) me because

nær er það minni ætlan að þeir þykist nokkuð eiga eftir sínum hlut að sjá við hann,
that is near my estimation that they bethink-themselves somewhat to have a cause belonging-to themselves (they have some personal justification) to see against (see to, take action against?) him,

utanhéraðsmennirnir, er nú munu brátt koma á hendur oss."
the persons-from-outside-districts, who now will quickly come against us.”

Og er þessu var skipað með þessum hætti þá komu þeir Þorsteinn og svo
And when (it) was arranged to this (note: dat sg) with this conduct (pl of háttr) (when they had put this in order in this manner?), then they, Þorsteinn (and co) came and also

Víðdælir og voru þeir hinir óðustu. Eggjaði Hallur Guðmundarson mest og
(the) Víðdalers and they were (the) most-mad (spoiling for a fight). Hall Guðmundr’s-son urged (the) most and

Kálfur Ásgeirsson að ganga skyldi að Bolla og leita Ósvífurssona þar til er
Kálfr Ásgeirr’s-son that (they) should attack Bolli and seek (the) sons-of- Ósvífr until

þeir fyndust og sögðu að þeir mundu hvergi úr héraði farnir. En með því að
they should be-found and said that they would nowhere (or by no means, not at all?) (be) gone out-of (the) district. But with that that (ie because)

Ólafur latti mjög að fara þá voru borin á milli sáttmál og var það auðsótt
Ólafr much dissuaded to go (ie he dissuaded them from going), then words-of-reconciliation were exchanged (lit: born) between (them) and that was easily-sought

við Bolla því að hann bað Ólaf einn ráða fyrir sína hönd en Ósvífur sá engi
with Bolli because he asked Ólafr alone to deal on his behalf (lit: be-in-charge of his hand, see ráða fyrir, Z16) but (and) Ósvífr saw no

sín efni að mæla í móti því að honum kom ekki lið frá Snorra.
reasons (condition) of his (ie he was in no position) to speak against (it) because no assistance came to him from Snorri.

Var þá lagður sættarfundur í Ljárskógum. Komu mál öll óskoruð undir Ólaf.
A reconcilation-meeting was then set (arranged) in Ljárskogar. All matters came without-reservation under Ólafr (ie under his arbitration).

Skyldi koma fyrir víg Kjartans svo sem Ólafi líkaði, fé og mannsektir. Síðan var slitið sættarfundi.
For the slaying of Kjartan should come (ie be determined) money (fines) and banishment (outlawry) just as pleased Ólafr. After that (the) reconciliation-meeting was closed.

Eigi kom Bolli til sættarfundarins og réð Ólafur því.
Bolli came not to the-reconciliation-meeting and Ólafr counselled that.

Gerðum skyldi upp lúka á Þórsnessþingi.
(One) should deliver the judgements (note: gerðum = dat plural, see and cf lúka upp görð, Z5) at Þórsness-Thing.