Here’s my translation

Alan

Hann horfir beint í móti dyrum ok þekkir hvat, er inn kemr, ok er því engu lífs at vænta, sem verðr fyrir hans klóagangi eða eitri. 
It (He) faces (lit:turns) directly towards (the) doorway and perceives (þekkja, not þykkja) whatever comes in, and (one) is to expect no life for that (því) (being) which is-in-the-way of its (his) clawing or poison (possibly:malice).

Þræll einn er í hofinu; hann vaktar mat gyðjunni. 
A lone slave is in the-temple; he watches (the) food for the priestess.

Tvævetra kvígu þarf hún í mál. 
She needs a heifer of two-winters for (her) meal.

Undir þessum gammi er egg þat, sem þú ert eftir sendr. 
Under this vulture is that egg, which you are sent after.

Griðungr einn er í hofinu, trylldr ok blótaðr. 
A lone bull is in the-temple, turned-into-a-troll and cursed (blota, (að), Z.ii).

Hann er bundinn með járnviðjum. 
He is bound with iron-withes

Hann skal skjóta kvíguna, ok blandast þá ólyfjan við hana, ok tryllast þeir allir, sem af eta. 
He shall shove (penetrate, mount?) the-heifer, and (his) ‘poison’ is-blended-(by-intercourse, double meaning?) with her, and all those who eat from (her) are-turned-into-trolls.

Hana skal matgera fyrir Hleiði konungs systur, ok verðr hún þá líka tröll, sem hofgyðjan var áðr. 
(One) shall cook (cf matgerð, noun) her (ie the cow) for Hleiðr (the) king’s sister and she becomes then like a troll, as the temple-priestess was already.

Nú þykkir mér óvænt um, at þú munir sigra óvætti þessa, við svá mikinn tröllskap sem um er at eiga."
Now (it) seems to me unlikely concerning (that), that you will overcome this monster, with such great “trollery” as (one) is having to deal with (vera with inf, Z6 + eiga um við e-n, Z10).”

Bósi þakkar henni nú sögu sína ok gerði henni góðan danganda í skemmtanarlaun, ok fór þá báðum vel, ok sváfu þau nú allt til dags. 
Bósi thanks her now for her story and made for her a good sharpening (?) (cf dengja?) in reward-for-enjoyment, and (it) went then well for both, and they slept now completely until morning (lit: day).

En at morgi fór hann til Herrauðar ok sagði honum, hvat hann hafði frétt, ok dvöldust þeir þar þrjár nætr, ok sagði bóndadóttir þeim, hvat þeir skyldu stefna til hofsins, ok bað hún vel fyrir þeim at skilnaði. 
But (And) next morning he went to Herrauðr and said to him, what he had heard, and they stayed there three nights, and (the) farmer’s-daughter said to them, in what direction they should go to the-temple, and she bade well for them at parting.

Fara þeir nú leið sína.
They journey (present tense) now (on) their way

Ok einn morgin snemma sá þeir, hvar maðr fór mikill vexti í grám kufli. 
And one morning early they saw, where a man large in stature journeyed in a grey cowl.

Hann leiddi með sér naut. 
He led cattle with him.

Þeir þóttust vita, at þat mundi vera þrællinn, ok stilltu þeir nú at honum. 
They bethought-themselves to know, that that would be be the-slave, and they walked-with-measured-noiseless-steps (stilla, Z5) towards him (ie snuck up on him).

Bósi sló hann kylfuhögg svá stórt, at þat var hans bani. 
Bósi struck him a blow-with-a-club so great, that that was his cause-of-death

Síðan drápu þeir kvíguna ok flógu af henni belg ok stöppuðu upp með mosa ok lyng. 
After-that they killed the-heifer, and flayed (the) skin from her and stuffed (it) up with moss and ling (heather).

Herrauðr fór í kufl þrælsins ok leiddi eftir sér kvígubelginn, en Bósi steypti kápu sinni yfir þrælinn ok bar hann á baki sér, þangat til at þeir sá hofit. 
Herrauðr journeyed in the-slave’s cowl and led behind him the-skin of-the-heifer, but (and) Bósi) cast his hooded-cloak over the-slave and carried him on his back, till that time that they saw the-temple.

Þá tók Bósi spjót sitt ok rak í rass þrælnum ok neðan eftir honum endilöngum, svá at oddrinn kom út við herðarnar. 
Then Bjósi took his spear and drove (it) into the-slave arse and from-below through him from-one-end-to-the-other, so that the-spear-tip came out by the-shoulders.

Ganga þeir nú at hofinu. 
They go now to the-temple.

Herrauðr gekk inn í hofit í búningi þrælsins. 
Herrauðr went inside into the-temple in the-slave’s attire.

Hofgyðjan var þá í svefni.
The-temple-priestess was then a-sleep.